I am interested in finding out which of these two tools is better. I'd also like to hear from different developers about their experiences (whether successful or not) using either or both of them to increment sales and visibility on the market, and of course if it is really worth implementing it on a game (in my case a puzzle game, only have 1 month left of development time to finish/deliver the game...). Thx in advance. ^_^
I choosed between them a few months ago and picked game center - mostly because it just seemed to make more sense to go with the "native" choice. Apple provides an example called gktapper and I based (read stole) my code on that example to get game center up and running in a day. A drawback with game center compared to open feint is that game center has no build in way to save state if you for some reason can't submit the score/achivement (no network etc) so you need to implement that yourself and make sure to try to resend it the next time the user launches the game with a connection. There is also the issue that the user might multitask and change user in the game center app itself while your app is running, a case I decided to ignore although you can listen for an event when it happens. I also find that the simulator often crashes when reporting to game center, something I've never seen on the device itself (but it makes me nervous thinking there might be something wrong). Since my first game is "only" ready-for-sale but not available I know nothing about how it affect sales etc but since it is fairly easy to implement I see no reason not to do it.
I plan on implementing both within my game. The main advantage I would say for GameCenter is its Apple's own service so everyone will be aware what it is. However the main reason I'm implementing OpenFeint is it supports iOS firmwares less than 4.0, in other words people who have the iPhone 3G, and thats still quite a lot of people. And OpenFeint make it quite easy to implement both so I've heard.
Be careful when taking stuff from GKTapper. When implementing stuff from GKTapper in a few games I had the privilege to work on, I ran into a couple of subtle bugs. (Hopefully I'm allowed to post links. If not, I can copypaste the article.) Now back to the OP. I've also worked with OpenFeint. OpenFeint is great because it allows me to distribute socially-enabled game for iOS 3.x devices as well. It has a couple of neat features: for example, offline mode. It also comes with the source code, so if you really have to modify something, you can. (I would be very careful, though.) OpenFeint provides Challenges, which, to my knowledge, Game Center does not. OpenFeint has some cross-app promotion mechanisms, but I have no experience with that. OpenFeint provides an alternate SDK that uses their API, but, instead of implementing their GUI, simply uses Game Center. OpenFeint guys are also quite reachable, and friendly. There are major drawbacks, however. Offline mode behaves a bit different than online mode. Leaderboards cannot have time format: while essential for our game's survival mode, we couldn't do it easily, so we ended up just displaying the seconds. Source code, if manually compiled, is suggested to be included in the app's project itself, greatly increasing compile time. (Even dependency precalculation takes too long.) You could compile it like the official release it built, but we opted to just go with the official build. OpenFeint loads nearly instantly on new devices, but takes a couple of seconds on first generation devices. Game Center also has multiplayer matchmaking. What are the drawbacks of Game Center? Well, for one, player has to be on iOS4.1+. Also, iPhone 3G doesn't have GC even with iOS4.1+. That may not matter for you. However, note that if player opts out of Game Center, all functionality that depends on it simply dies. You could write an intermediate layer that would work offline as well, but meh. So far, the first game I've coded by myself uses OpenFeint. I intend to keep OpenFeint in the game, but also add Game Center at a later stage.
I chose to use Game Center for The Creeps! because the first solution I tried (Agon) went out of business because of Game Center. Also, I don't plan on porting it to Android. Plus, I don't like all the ads and clutter in OpenFeint... from a user's point of view Game Center is much more simple, streamlined and easy to use. I like simple and easy. I might consider OpenFeint in the future because it is exremely popular and it does have (many) more features than GC, but by the time my next game is done I'm sure there will be a new version of Game Center...
