Derek Yu’s Spelunky (in Game Maker for PC and coming soon to xBox Live Arcade) has been attracting a lot of attention on Indie Gaming sites recently whilst remaining noticeably absent(??) from YoYoGames.com and the official Game Maker Community.
Spelunky is a platform game in which you explore caves to collect treasure. Each game is different as the caves are regenerated every time you play. You go around fighting enemies, avoiding obstacles, opening chests and collecting rewards. The game comes complete with a level editor and it is easy to share user created levels with other gamers.
The source code (in Game Maker 8 ) was released on Christmas Day and can be downloaded here.