So I thought I'd make a topic about Spelunky. You can get the game on Steam for 14€, it's not that expensive. It's a lot of fun and all caves are randomly generated, so no attempt is ever the same.
Here's some information and a link to the Steam page.
Just post interesting stuff that you found in the game or just if you beat the game for the first time. It's a pretty difficult game, so beating it is quite an achievement.