Ben Dodson, author of various Gowalla related tools in the past, has released Wallabee, a location based game he’s been working on the past few months:
WallaBee is the ultimate collectibles game for your iPhone. The aim of the game is to complete sets by collecting items in a variety of ways. Each item and set is uniquely numbered so you’ll need to be quick if you want to beat your friends to the lowest numbers!
As he says so himself:
I like to call it “The ultimate collectables game”. It’s a mixup of several ideas from things such as Gowalla, Pokémon, PackRat, and Baseball Trading cards
Think of it as the items part of Gowalla, but then with some clever additions (some of them were suggested to Gowalla back in the day) such as mixing items (think Doodle God)