Zaga-33 is an exercise in how minimal a roguelike can be. Originally developed in seven days, it’s a nice example of how minimalism and depth are not mutually exclusive. There’s a strong focus on movement and evasion. To succeed requires the ability to accurately predict how the enemies will behave and a little bit of luck.
There are five single-use items and seven enemies. Every attack does one point of damage, and every enemy has two HP. The score is the number of levels traversed (plus a bonus on game completion). That’s about all there is; the mechanics are very tight.
Windows / OS X: http://mightyvision.blogspot.com/2012/04/zaga-33.html
There is also a paid iOS version, should you desire the “Zaga!” intro sound to be ever at your side.