Is anybody download the PaPi games from market and played it?

I found when I played one of this series of PaPi game and I input my name,then all series PaPi games can read this name.

At beginning, I consider maybe the application saved some data which can be shared by other PaPi games, but when I "Factory data reset" and format the SD card, then I download these games and play them again, it's so crazy that these games can read my name which I inputed before all the same!!

next, I consider maybe the application read the only code of the phone(IMEI) to identify the phone,but I check the install information about all the PaPi games, I can't found any information about "READ PHONE STATE",so I think these applications didn't read the IMEI code.

who can tell me how to achieve this function?! thx!