WO2005061067A1

WO2005061067A1 - Method and device for difficulty level adaptation of a network based game

Info

Publication number: WO2005061067A1
Application number: PCT/IB2003/005937
Authority: WO
Inventors: Reza Serafat
Original assignee: Nokia Corporation
Priority date: 2003-12-15
Filing date: 2003-12-15
Publication date: 2005-07-07
Also published as: AU2003285619A1

Abstract

The present invention relates to a method and a device for network gaming and mobile gaming and more specifically to the field of multi-player gaming. The present invention provides a method and a device to adapt a difficulty level of a network based game for participation of at least two game terminals by determining a quality of connection in said network separately for each of said game terminals participating in said network based game, and adapting said difficulty level according to said determined quality of connection separately for each game terminal.

Description

Method and device for difficulty level adaptation of a network based game

The present invention relates to the field of network gaming, mobile gaming and more specifically to the field of online multi-player gaming. The invention is related to the improvement of user experiences while playing a multiparty game based on cellular network based games. More specifically, the invention relates to a method and a device for the use with mobile online multi-player games between mobile terminal devices, wherein the transmission quality of the radio connection is determined to prevent that single players experience unjust advantages or disadvantages.

Presently, there are different online games available. The document DE 100 26 853 C2 discloses a Wireless Application Protocol (WAP) based cellular network game. In the disclosed game architecture, the influence of the quality of a radio based connection between a terminal device and the other players or a server is less critical in the case of strategy games or for example board games or dice games. Strategy based games can be played even completely without any time factor, as e.g. in the case of correspondence chess, as every player can only make his move after the other player has made his move.

In case of speed or reaction based games such as action-, sports- and combat-games or in the case of racing- or flight simulations the time factor can work to the player's advantage or disadvantage. The user experience of multiparty mobile gamers will suffer from the variation of quality of connection or a quality of services of a cellular network, if some players can benefit from game skill independent parameters, this would be experienced like playing a board game with forged or false dice.

From the document US 6,475,089 it is known to alter the skill-level of the single participants in Internet multi-player games, on the basis of the behavior history of the single players to achieve comparable chances for the single players to win. That is, the US 6,475,089 document discloses a kind of automated handicap system for electronic multi-player Internet games.

In the case of hardwired online games such as e.g. Internet based games, the connection quality from or to the involved users can be measured at the beginning of the game and the game synchronization can be fixed depending on the performance of the connection with the lowest quality. This has been possible as the connection quality in hardwired online games is supposed to be substantially constant.

In earlier solutions the participants with a good connection quality could not exploit their capabilities and experience the best quality of connection. This will lead to a reduced gaming experience if one participant in the game session had a bad connection quality, because skilled players would not get the best gaming experience which they actually could get.

It is therefore desirable to prevent that the user experience of multiparty mobile gamers will suffer from any variation of the quality of the online connection.

This invention proposes a method and a device to compensate the quality of connection dependencies to online reaction time based gaming and to improve the user experience.

This invention also proposes a method and a device to compensate the quality of connection dependencies and influences to mobile wireless online reaction time based gaming.

According to a first aspect of the present invention, there is provided a method for the adaptation of difficulty levels in network based games. The method comprises determining a quality of the data connection in said network separately for each of at least two game terminals( or players) participating in a network based game, and adapting the individual levels of difficulty according to said determined quality of connection separately for each of said game terminals (or their players).

By determining a quality of connection in said network separately for each of the at least two players participating in a network based game the influence of changes in the transmission chain between different network gamers caused by variations in the transfer characteristics can be compensated. The present invention is directed to be applied in online network gaming, wherein the connection of a server to a participant or to his terminal device can be subject to different and possibly varying transmission conditions resulting in different and possibly varying data transfer rates and data transfer times. For example, one terminal device can be connected via a conventional acoustical coupler and a telephone line, another via a modem, and another device can be connected via a DSL (Digital Service Line) modem connection. With these different connection types the data transfer rate and the data transfer time from the terminal devices to a serve device can differ from each other.

The quality of connection in said network can determined by using e.g. a signal to noise ratio, an actual data transfer rate or a determined data transfer time. The quality of connection in said network can be determined by analyzing e.g. a block error rate or a frame error rate in packet transfer based networks i.e. to follow up the number of received and not or falsely received data packets during the online gaming connection.

The data transfer time of game input data is in the case of timing-critical games such as e.g. reaction-time based games such as action games, jump-and-run games or racing games can have a decisive influence on the game score or the game result. A player with a connection with a slower data transfer may even loose his chances of winning. This fact may even influence the commercial success of cellular network gaming.

The measurement can also be performed only once before starting of the game. One aspect of the invention is to define different individual transmission quality levels for each game terminal, dependent on connection quality.

By adapting a level of difficulty according to said determined quality of connection separately for each of said players, each player can be provided with an individual gaming advantage to even out the handicap caused by the data transfer delay. It is for example possible to reduce the number of targets, change the characteristics of opponents, shorten an input delay or increase a tolerance limit, or broaden a timeframe for a game input.

In an example embodiment of the present invention, said network is a wireless network. If applied to wireless networks, the present invention is directed to mobile network gaming, wherein the connection to a mobile participant or to his terminal device can be subject to varying transmission conditions resulting in varying data transfer rates and data transfer times. For example, in the case that the wireless network is a cellular communications network, the data transfer time in adjacent cells can vary, and therefore a game terminal or player changing from one cell into an adjacent cell can suffer or benefit from changed data transfer times.

In an example embodiment of the present invention, said wireless network is a cellular communication network. The cellular mobile network can be a mobile cellular telephone network such as GSM (Global System for Mobile Communication), UMTS (Universal Mobile Telecommunication System), or one of the following future cellular telephone standards. It is also possible to use e.g. a non-cellular telephone system such as satellite based telephone systems.

In the field of the Cellular Network Games there is a wide variety of different radio connections with different data transfer qualities available such as e.g. GSM (Global System for Mobile communication), GPRS/EDGE (General Packet Radio Service/Enhanced Data rates for GSM Evolution), HSCSD (High Speed Circuit Switched Data), 3G (3^rd Generation UMTS (Universal Mobile Telecommunication System)/WCDMA (Wideband Code Division Multiple Access)), but also WLAN (Wireless LAN) Bluetooth connections are available. These different types of radio connections maybe summarized under the expression "connection services", as one of these data transfer modes represents more of a kind of data transfer service than a direct permanent communication connection. For the purpose of simplicity, the expression "quality of connection" is used to describe the quality of any kind of connection service provided by a wireless network. These different types of connections or connection services are also subject to the problem of a time variance of the quality e.g. the transfer rates and the transfer times of the connections. In the case of GSM radio connections the data transfer time can vary for the reason of a weak connection or interference between the mobile terminal and the base station.

In future CDMA (Code Division Multiple Access) based cellular communication techniques the data transfer time can also be strongly correlated to the number of (active) cellular terminal devices within a cell. CDMA-systems are also capable of performing "Cell Breathing" wherein the area of the cells can be individually varied according to the present requirements. The quality of connection can vary because of the Cell-Breathing. Also in the case of the GPRS based data transfer the quality of connection of a single data connection can vary according to the number of available GPRS-data channels and GSM-voice channels. These variations are caused by the possibility of regular adaptations of the number of uplink- and downlink-channels in case of data transfers with high data rates.

In Cellular Network Gaming not only the radio transfer technology used and the actual data traffic load in a cell is to be taken into account by determining the quality of connection, but also the basically static quality of the connections between the base stations and the games server. The games server itself may be connected via an Internet gateway to the cellular communication network, which in turn contributes to the overall comiection quality between the games server and the connected mobile game terminal. In case of local radio connections between game terminals, such as Bluetooth, the quality of the radio connection can also vary, if for example a game terminal is located at a grater distance to a master device than another game terminal. It may be noted that the present invention is not to be restricted to cellular telephone networks. The present invention can also be applied to local wireless networks wherein one of the game tenninals can have the master role or the game server role. In this case the master/game server terminal can simultaneously serve as a game terminal and as a games server device, using the method of the present invention, to play fairly, even in an environment with an unfair distribution of the qualities of connection.

It is also possible to apply the present invention in distributed wireless gaming architectures wherein the game software is present on all the game terminals and the game terminals execute the game software as equal partners. In this case each of the devices is in the mater role and can provide the players of connected game terminals, but not the player of the device itself, with a quality of connection based difficult level.

hi yet another example embodiment of the present invention, said quality of connection is determined by monitoring transmission parameters. The quality of connection in said network can be determined by analyzing e.g. a block error rate or a frame error rate in packet transfer based networks i.e. to follow up the number of received and not or falsely received data packets during the online gaming connection. Such kind of measurement is for example described in the European patent application EP 953267 and international patent application WO 03/08855.

In networks that use for example Automatic Repeat Request (ARQ) or Hybrid- ARQ (HARQ) techniques, the time between the sending of a data packet and trie reception of a respective acknowledgement/non-acknowledgement (ACK NACK) signaling can be used to determine a measurement for the actual quality of service. In ARQ it is also possible to use information coded in the ACK/NACK signaling to determine an actual quality of service measurement.

In the case of a wireless connection the quality of comiection can also be determined by monitoring the actual data transfer. In Bluetooth the correct transmission of a data frame or data packet is acknowledged by a dedicated (ACK/NACK) signaling. Such a procedure is for example proposed in the document WO 03/043218. On the basis of this technique the data transfer quality of a channel can be determined indirectly, without using additional data transfers of quality determining data packets (as long as these ACK/NACK messages are prescribed in the Standard of the transmission).

In another example embodiment of the present invention said determining of the quality of connection is performed by using round-trip-time measurements. The round trip time (RTT) can be defined by the time that is required for a data packet to be transfened from the game server device to the mobile terminal device and back again. The round trip time (RTT) may be defined as the time between a sending of a data packet and the reception of an ACK signaling. The round trip time (RTT) can be measured for example by using dedicated round trip time data packets that are to be transferred from the game server device to the mobile terminal device and back again. A round trip time data packet received by a game terminal is to be sent back to the sender immediately. A more sophisticated round trip time data packet may also add a kind of calculation surcharge in the terminal device before it is returned to the sender to take differences in the execution speed of a terminal games software into account. A round trip data packet can be send by the game server via the network to a game terminal, and back again. The terminal device receives the data packet and sends it immediately back to the sender, e.g. the game server. That is, the RTT represents the time that is required for sending a data packet to the game terminal and sending it back to the server.

It may seem that this information is not sufficient, as the downlink- and uplink-time can not be determined separately but only the sum of both times i.e. the round trip time can be determined. For the present invention it is not important if a time lag occurs on the uplink side or on the downlink side of the data communication. In both cases, the player is provided with the game data at a later moment in time, or the player has a limitation by the time lag in reacting to a received game event.

By using round-trip-time data packets it is not relevant which special transmission mode is actually used in the different section of the data transfer between the games server and the game terminals. It is actually not relevant for a RTT data packet at which point in the data transfer chain a time lag is caused. The RTT data packet can determine a time lag in a data connection without being able to find its cause.

In yet another example embodiment of the present invention, the use of said round-trip-time (RTT) data packets is related to the actual data load of the data connection. By this feature it may be prevented that the RTT data packets further reduce the data transfer between the games server and the game terminals. Thereby it may be prevented that the RTT data packets can reduce the gaming experience. It is also possible to increase the number of RTT data packets to increase the accuracy of the determination of the quality of connection between the games server and the game terminals, as long time lags need to be determined more exactly than short time lags.

In yet another additional example embodiment of the present invention, said quality of comiection is determined repeatedly. Said quality of connection can also be determined regularly, wherein the expression "regularly" is been selected to describe that a quality of a connection is determined repeatedly, according to a rule, which can also comprise determine the quality of connection at randomly selected points in time or randomly selected distances.

In yet another additional example embodiment of the present invention, said quality of connection is detennined periodically. Thereby e.g. the round trip time (RTT) data packets can be dispatched at regular time distances for example every few microseconds, every few milliseconds or every few seconds. It may also be possible to dispatch the RTT data packets every few tens of seconds, every minute or every few minutes in regular intervals.

The determination can also be performed periodically, wherein the length of said period should be within proper limits e.g. as determined by the characteristic time scale for the variations of the quality of comiection. It is also possible to use the perception by the player of the variations as a basis. It is also possible to use algorithms to change the periodicity in accordance with the variation properties of the quality of connection. The period for determining the quality of connection should not provide a perceptible additional data load for the communication between the game server and the game terminal. In case of directly wirelessly connected devices it is for example possible to use the signal to noise ratio as an indicator for the quality of connection.

In another example embodiment of the present invention, said quality of connection is determined in an event-controlled manner. In the case that RTT data packets can be dispatched synchronously to the communication packets e.g. following every 2^nd, 5^th, 8^th, 100^th or n^th game data packet. It is also possible to use e.g. every n^th player input to control an algorithm to reduce the communication and calculation load for the game server. It is also possible to determine a game inherent parameter reflecting e.g. the actual difficulty in the game to increase the number of measurements.

hi yet another example embodiment of the present invention said quality of connection is determined according to an average value over time. By determining a variation of the round trip time it may be possible to ignore single RTT packets with very high or very low round trip times. In case of a strong variation e.g. based on signal fading in case of moving game terminals, the difficulty level may be held on an average level based on two or more RTT measurements in the past.

hi yet another additional example embodiment of the present invention, said adaptation of the level of difficulty is performed in a smoothed manner. Thereby, it may be prevented that game parameters such as e.g. time frames for a single input may be scattered, i.e. opened on detection of a normal RTT, subsequently closed upon receiving a very short RTT and re-opened after the reception of another very long RTT. The smoothing may be implemented by a limitation of the variation of the level of difficulty.

In a further example embodiment of the present invention, said adaptation of the level of difficulty is performed by varying the length of input time frames. By broadening time frames or by moving time frames, a player input or a game terminal input may actually be detected within time, even if the input is received from a terminal device with a time lag. By broadening or extending time frames, other game parameters that are related to the difficulty level of a game may not be changed. For example in a clay pigeon shooting game the size of the pigeon stays the same while the "length" or the duration of a "shot" is increased.

According to yet another aspect of the invention, a software tool is provided comprising program code means for carrying out the method of the preceding description when said program product is run on a computer or a network device.

According to another aspect of the present invention, a computer program product downloadable from a server for carrying out the method of the preceding description is provided, which comprises program code means for performing all of the steps of the preceding methods when said program is run on a computer or a network device.

According to yet another aspect of the invention, a computer program product is provided comprising program code means stored on a computer readable medium for carrying out the methods of the preceding description, when said program product is run on a computer or a network device.

According to yet another aspect of the present invention a network game server is provided. The network game server comprises a network interface, a processing unit, a storage, a determination component and an adaptation component.

The network based game server can be equipped with a software program, which checks frequently the connection quality of the game participants.

The network interface can be a connection to a telephone network, the Internet, or the hardwired side of a cellular telephone network. It is also possible that the network interface is a short-range air interface such as a Bluetooth interface, a W-LAN interface, or an infrared-based interface.

The processing unit is provided to run game software and/or game server software. The processing unit is connected to said network interface to exchange game data with game terminals connected via said wireless network.

The storage is provided to store player identifications and difficulty levels, related to each of said player identifications. The storage is connected to said processing unit.

The processing unit is configured to execute game software with mobile game terminals connected via said network interface according to the data stored in said storage. The storage can be a persistent data storage or may also be main memory of the game server.

The determination component is configured to determine at least once the qualities of comiection in said network separately for each player is connected via said network participating in a wireless network based game. The determination of the qualities of connection can also be performed regularly. The determination component is connected to said network interface. The determination component can be connected directly to the network interface or indirectly via said processing unit.

The adaptation component is configured to adapt the level of difficulty, according to said determined qualities of connection separately for each of said game terminals. The adaptation component is connected to said determination component and to said storage. Therefore, the adaptation component can change the level of difficulty used for executing a network game individually for each of said identified players participating in an electronic online game running on said server. It may be noted that the expression "wireless" can be related to the network, but not necessarily to the game server.

The network game server can be a wireless network game server. The connection quality of the game participants may be measured by sending a measurement data package to the mobile device. The game client running on the mobile device re-sends the measurement data packages immediately back to the game server. The software program located at the game server measures the round trip time of each package and determines the delay to be able to control the individual levels of difficulty of each game participant accordingly.

In an example embodiment of the present invention the wireless network game server is incorporated in a mobile terminal device. This embodiment of the present invention pertains for example to wireless game server for wireless local area networks. It is for example possible to incorporate the game server in a mobile telephone device for example in a GSM telephone, an UMTS telephone or the like. It is also possible to implement the present invention in a wireless local data exchange enabled game terminal based e.g. on Bluetooth, W-LAN, Infrared or the like.

In the following, the invention will be described in detail by referring to the enclosed drawings in which: Figure 1 is a flowchart of an embodiment of a method for adapting a difficulty level wireless network based games according to a detected quality of connection,

Figure 2 is a flowchart of an example of a method for detecting a quality of connection, and

Figure 3 is an example of a wireless network game server connected to mobile game terminals via a wireless network, according to one embodiment of the present invention.

Figure 1 is a flowchart of an embodiment of a method for adapting a difficulty level in wireless network based games according to a detected quality of connection. The quality of radio connections in general and especially in cellular networks is varying heavily depending on several parameters. Therefore, the performance experienced by the participants in multiparty cellular network games will also vary depending on the variation of data throughputs and possible delays. Accordingly, the players with a better connection quality have a better chance to win the games in comparison with those located in bad coverage area. This is even more important for players moving relative to the base stations for example players playing in trains, as the data transfer is affected by multi-path interference, fading, permanently changing terminal base station distance and so on. The cunent invention intends to compensate the effects of quality of connection variation from the player' s point of view.

If a game servers starts is service 40, and executes an online game with at least two game terminals 42 via a wireless connection, the game server located on the network: side will measure frequently the connection quality 44 between the game server and each of the connected mobile game terminals. Subsequently, the game server individually adapts the game difficulty levels for each connected game terminal (or player) according to their individual connection quality 46. Following this, the online game is executed with the adapted difficulty level via until a next determination and adaptation cycle 44-46 is performed, or the execution of the game is terminated 48. It may be noted that the execution of the game is not necessarily interrupted for the determination and adaptation cycles but can also be performed regularly or constantly and parallel to the execution of the game at the server.

Thus, the effects of varying data transfer rates and data transfer times in network gaming can disadvantageously affect the game experience for the players. The present invention proposes to overcome this disadvantage by regularly/constantly measuring the quality of the network connection of the players and adapting the game level for the players in order to achieve the same game chances for all players. Figure 2 is an example of a method for detecting a quality of connection by using round trip time data packets. The quality of connection in cellular networks can vary considerably based on the network configuration of cells and their capacities. In case of playing cellular network based games, users with low connection quality experience a disadvantage in game participation and have less chance to win the game session, although under normal conditions they would play at a higher level. This decreases the user experience in case of high transfer times between the game server and the gaming device considerably. This disadvantage may be compensated, if the network based game server is aware of the individual connection qualities of all game participants and can individually adapt the game difficulty levels accordingly.

For this purpose the game server measures the connection quality of each of the game participants frequently and periodically by sending them a specific data package and measuring the round trip time of such package. Depending on the measured delay the game server changes the game difficulty level of the participants.

In figure 2 the depicted flowchart represents an embodiment for determining the quality of comiection, indicated in figure 1 by the reference numeral 44. Thus, the boxes 50 52 and 54 of figure 2 are framed by the box 44. To indicate the relative position in figure 1 there are also the boxes 42 and 46 added. One possibility to determine the quality of connection is to measure the Round-Trip-Time (RTT). The quality of connection is determined by sending or dispatching a RTT data packet 50 via the wireless connection to a game terminal. The round trip time data packet can be embodied as an one-to-many data packet or preferably as an individual round trip time data packet destined only to a single game terminal. The round trip time (RTT) data packet is to be received by a game terminal to be immediately returned to the sender. The game server then again receives 52 the returned RTT data packet. The RTT data packet is supposed to experience no significant time lag in the game terminal between reception and returning of said RTT data packet. The game server can determine the time between the sending and the subsequent reception of the RTT data packet as a measure for the quality of the two way communication connection. The time period between the sending and the reception of the returned RTT data packet represents the minimum reaction time of a player in the online game to a game event sent to a player.

The usage of Round Trip Time measurements is only one example for determining the quality of a connection. Other methods, known to persons skilled in the art, might be used. If the used data transmission system allows e.g. to follow up the number of received and not or falsely received data packets during the online gaming connection, this information can also be used for determining the quality of connection and adapting the game difficulty level. Such kind of measurement is for example described in the European patent application EP 953267 and international patent application WO 2003/08855.

The game server can use e.g. a pre-determined table that assigns different round trip times to different game difficulty levels. It is also possible to combine the present invention with other handicap systems to enable online gaming between players in a wireless network environment with different qualities of connection.

Figure 3 depicts an embodiment of a wireless network game server connected to mobile game terminals, according to one embodiment of the present invention. The depicted wireless network game server 2 is connected via a network interface 4, and via a wireless communication network 18 to the game terminals 16, 20.

Each of the connected game terminals 16, 20 might be connected by a different kind of wireless communication network to the game server 2. For example game server 16 uses a high data rate GPRS connection to the game server 2, while game terminal 20 is using a lower data rate GSM connection to the game server 2. Even if the GPRS connection usually provides a higher data rate connection to the game server 2 it is possible that, due to bad networ coverage or many terminals in the same cell using the GPRS connection, the transmission speed and/or data rate of the GPRS connection of terminal 16 is even lower than the GSM connection of terminal 20. The game terminals 16,20 might be mobile phones incorporating mobile gaming functionality such as the Nokia N-Gage ™.

The game server 2 also comprises a processing unit 6, that is connected to said network interface 4 and a storage 8 that is connected to said processing unit 6. The processing unit 6 and the storage 8 are provided to execute a multi-player network game with game terminals 16, 20 connected via said wireless network 18 and interface 4. The storage 8 is provided to store player (or terminal) identifications, individual difficulty levels, and individual scores.

The games server of the present invention further comprises a determination component 10 that is configured to regularly determine a quality of connection of said wireless network 18. To be able to perform this, the determination component 10 is connected to said network interface 4. The determination component 10 can also be connected to said processing unit 6 to receive information related to the participating players. The determination component 10 can also determine the information related to the participating players by surveying the data exchange of the network interface 4. The determination component 10 determines separately for each connected player at least one individual quality of connection parameter, and regularly updates this parameter by monitoring the qualities of connection.

The game server 2 further comprises an adaptation component 12, which is connected to said determination component 10 and to said storage 8. The adaptation component is configured to adapt the level of difficulty stored in said storage 8 according to said determined quality of connection parameter separately for each of said players.

This application contains the description of implementations and embodiments of the present invention with the help of examples. It will be appreciated by a person skilled in the art that the present invention is not restricted to details of the embodiments presented above, and that the invention can also be implemented in another form without deviating from the characteristics of the invention. The embodiments presented above should be considered illustrative, but not restricting. Thus the possibilities of implementing and using the invention are only restricted by the enclosed claims. Consequently various options of implementing the invention as determined by the claims, including equivalent implementations, also belong to the scope of the invention.

Claims

1. Method for the adaptation of a difficulty level of a network based game for participation of at least two game terminals, comprising: determining a quality of connection in said network separately for each of said at least two game terminals participating in said network based game, and adapting said difficulty level according to said determined quality of connection separately for each of said at least two game terminals.

2. Method according to claim 1, wherein said network is a wireless network.

3. Method according to claim 1 or 2, wherein said quality of connection is determined by monitoring transmission parameters.

4. Method according to anyone of the preceding claims, wherein said determination of the quality of connection is performed by using round-trip-time measurements.

5. Method according to claim 4, wherein the use of said round-trip-time measurement is related to the actual data load of the data connection.

6. Method according to anyone of the preceding claims, wherein said quality of connection is determined repeatedly.

7. Method according to anyone of the preceding claims, wherein said quality of comiection is determined in an event controlled manner.

8. Method according to anyone of the preceding claims, wherein said quality of connection is determined according to an average value over time.

9. Method according to anyone of the preceding claims, wherein said adaptation of the levels of difficulty is performed in a smooth manner.

10. Method according to anyone of the preceding claims, wherein said adaptation of the levels of difficulty is performed by varying game input time frames.

11. Computer program product comprising program code means stored on a computer readable medium for carrying out the method of anyone of claims 1 to 10 when said program product is run on a computer or network device.

12. Computer program product comprising program code, downloadable from a server for carrying out the method of anyone of claims 1 to 10 when said program product is run on a computer or network device.

13. Network game server comprising:

- a network interface, connectable to a communication network, - a processing unit, connected to said network interface, a storage connected to said processing unit to store connected game terminal identifications and difficulty levels, wherein said processing unit is configured to execute game software with at least two game terminals connected via said network interface according to the data stored in said storage, characterized by a determination component that is configured to determine a quality of connection of said network separately for each of said at least two game terminals connected via said network participating in a network based game, wherein said determination component is connected to said network interface, and - an adaptation component that is configured to adapt the level of difficulty according to said determined quality of connection separately for each of said at least two game terminals, wherein said adaptation component is connected to said determination component and to said storage.

14. Network game server according to claim 13, wherein said network game server is incorporated in a mobile terminal device.