Spelunky! [Free Version] - PC Games

Free Games (41 items)
list by Mr. Saturn

PC Videogames I Played 3 (408 items)
list by Sweet Shark

2012 To Play (67 items)
list by wordsasbombs

Probably the easiest way to describe Spelunky is that its (kind of) like La Mulana meets Nethack - every time you play the levels, items, monsters, and so forth, are all procedurally-generated. And the terrain is destructible and there are quite a few ways in which the various game elements can interact with one another.