Online gaming has become a very successful business. With millions of users daily, the server capacity required to host a system like that (e.g. World of Warcraft) is humongous. One of the interesting applications of P2P would be in MMOG’s. P2P can already deliver content in a very speedy fashion. A node in a P2P system can also take advantage of all its available bandwidth. A paper was recently presented in class that proposed a system called Donnybrook. Basically, they took the Quake III source code and modified it to include P2P networking and other tools I will mention to make the game play smooth. Two things they did that I thought were interesting were interest sets and doppelgangers. Interest sets are a set of equations that decide who out of all the players you are most interested in receiving real-time updates about. These equations use player proximity, field of vision, and other aspects of the game to choose the top 5 players in the game you are most likely interacting with. These interest sets change frequently, but they make it so you only have to receive real-time updates from a small number of players—you receive updates from the other players once per second. At first this raised a red flag in my mind when I thought, “well how do they smooth out the game play?” It wouldn’t be acceptable to have players jerking around the map. One of the other things they did that addressed this issue was implementing doppelgangers (i.e. bots). Basically, the game will measure player behavior and predict movement patterns. Therefore, during the time between the longer updates, bots are moving the players in the direction they think the players would have taken—pretty cool concept. The authors were able to achieve a P2P game of Quake III with 900 players using these techniques. That’s amazing!
I’ve previously mentioned that P2P systems cause ISP’s much consternation. If games move to a P2P architecture, will they be able to throttle the traffic like they are? I ask this question because, most people will not contest an ISP’s decision to throttle P2P traffic because they are likely downloading media illegally. But with games, there is nothing illegal about that. There could be some interesting business deals that come out such a gaming system. Another interesting thought would be to employ previously mentioned peer selection techniques to make sure that inter-ISP traffic was minimized. These techniques would also improve the throughput of the game. There are lots of interesting applications for P2P systems, but politics always seem to get in the way (tongue and cheek of course) of innovation.