Recently I sort of lost my gamecenter id (keldron) and gamecenter asked me to create another id which i did. Now there is something called "sandbox" which always appears in Gamecenter heading. Also the number of players in games are far fewer now. For e.g. in Bike Baron, there are only 23000 odd players, whereas earlier there used to be some 600,000 users. What am i missing or doing wrong?
You recently had a beta version of a game on your device with game center. And that makes you signed into the "sandboxed" version of game center which is for beta testing, and separate from your normal account. Go to the game center app itself, sign out, and sign back in to keldron. and everything will be normal again. If you go back into the beta, or get another one into the future, it'll ask you to resign back into your beta account.
I've seen this happen to people when they jailbreak their devices. Not really sure what causes it, might have to do with how jailbreaking rearranges/moves system files or alters permissions. One method that has fixed this for myself and others: 1. Create a new GC account and log in to it. 2. Open up any other app that uses GC and wait for it to login your new account. 3. Close GC and any other multitasking apps, then reopen GC and log out. 4. Log back into your original account.