Beta apps like Coolson's use a different, separate Game Center to the real one that apps from the App Store use. Apple calls it the "Sandbox" Game Center. You will need to create a Sandbox Game Center account when you first play Coolson's - it will prompt you. The Sandbox Game Center is entirely separate from the real one. You can use the same AppleID as you usually use, and hopefully your usual Game Center nickname will still be available in the Sandbox - if it's not, you'll need to choose another, I'm afraid!
An iPad can only be logged in to either the sandbox or the real Game Center. Launching Coolson's will automatically log you out of Game Center into Sandbox Game Center. Launching an App Store app that uses Game Center will log you out of the Sandbox Game Center and into Game Center. Launching the iPad's preinstalled "Game Center" app will not change which Game Center you're logged into; it will show the Sandbox if you previously played Coolson's, and the real Game Center if you previously played an App Store app.
This all sounds pretty harmless so far, but which Game Center you're logged into affects notifications. If you want to be able to receive Game Center notifications and invitations for your regular apps, you must remember to run one after playing Coolson's. For example, if you don't launch Letterpress after playing Coolson's, you won't hear about any turns other people took until you do. Conversely, if you want to be able to receive invitations to play Coolson's, it needs to have been the last Game-Center-using app you've run.
It's by no means compulsory, but a Sandbox Game Center friend request would be lovely - I'm 'th_in_gs', Em is 'thegrene'. You can friend people in the sandbox using the Game Center app after running Coolson's. Also, feel free to send us invitations to play - trying any time is fine if you are okay with not getting a response, but we're especially going to try to be available to play at 12 - 1 PM (lunchtime) Pacific time, 8 - 9 PM British time (and we'd love to get some transatlantic games going). You don't need to friend us just to do this during these times - just start up an Internet game and "Play Now" - it'll auto-match, and probably get us as there obviously aren't many Coolson's players at the moment.