What are some Steam games with good demos?

I like gunpoint

I am not sure of the demo, but Kerbal Space Program is a game I enjoy from time to time.

The Stanley Parable Demo, natch.

Shadow Warrior has one.

Hm, I would say continue playing Tiki Tori 2+ first. The later puzzles are more interesting than the start. Other than that if you like indie platformers I can recommand Fly'n. Hey, it seems I actually recommanded (if searching for more information) it. It has a demo to try out although I don't know what part of the game it covers. Probably something of world 1 which is still beautiful but not as interesting as the following ones.

Hm, looking through my library: A nice little puzzle platformer: The adventures of Shuggy. Collection of many short one screen levels. Every level is designed around one reoccuring core feature like using a rope, rotation, time shift ....

Hm and another one: The Maw. Also one of my reviews (if interested). Although this one is very easy. But I found it pretty charming and enjoyable.