Game ladder using Apple Game Center

Question

I'm implementing a turn based game where players can meet other players in matches via Apple Game Center. Each match has two players.

I want to make a global ranking of all players using Apple Game Center. This ranking serves two purposes:

• each player will know his/hers ranking.
• a player can be matched to another player with a similar skill.

My current thinking is something like this:

• A win gives +1 points
• A lose gives -1 points
• An aborted match, or not accepting a match gives -1 points.
• 0 is the minimum score.
• The leaderboard will present the score of each player.
• Players will be placed in groups according to their score. Each group can cover a range of scores, and players will be matched with players from the same group.

I have the following questions:

• Do you like my suggested scoring solution?
• Is it possible to accomplish an effective match making with this approach? I mean, some groups can have very few participants. Maybe only one. Of cause you can try to do a match making with a lower group, but that can also be empty, and it will take time. How shall I solve this?
• I've not released the game, and I don't know how many players it will have. Is it possible to make the grouping dynamic in some way? More players requires more groups.
• Is it possible to make players that does not accept matches to lose points? I only want to have active players in top of the ladder.

So far I've only found this input: https://stackoverflow.com/questions/9355799/can-i-make-a-ladder-systemlike-battle-net-with-using-just-game-center

Answer 1

I've made a scoring system almost exactly the same as you have with Game Center expect I use a more advanced rating algorithm (http://en.wikipedia.org/wiki/Elo_rating_system). I will answer your questions in order:

• Yes I think your idea sounds good.
• I've heard that apple automatically will pair people from different groups if there is no people in the same group. Nevertheless, you could define the groups by separating them with |. For example if you want players to match people with a score of +- 100 you could make something like GKMatchmakingObject.gruops = (int)player.score/100-1| (int)player.score/100 | (int)player.score/100+1
• Edit: NO, you will probably need an external server for tracking players online.

Yes there should be away to get an NSArray of all players in a specific leaderboard. That way you could for example use array.count and from that way increase the gap to +- 200 or +-300 if array.count is < 100. - Finally, yes. There is a delegate callback for when people decline which you could use for this purpose.