Intelligent and exciting indie games: my pick

Tag: The Power of Paint - some resemblances with Portal + have fun painting the levels. YT gameplay here.  [free] 

Crayon Physics Deluxe - draw and enjoy the laws of physics [demo available] 

Devil’s Tuning Fork - original game, hypnotizing visuals [free]

rCOMPLEX - run, slide, jump, shoot [free]. Trailer  Update: next (much longer) version will be released this month.

NightSky - have a look at a game which will test some ppls skills and creativity: trailer [free]

Cogs - classic puzzle game [demo]

Gunpoint - really liked its complexity [free]

The Cat and the Coup  - docugame about the first democratically elected Prime Minister of Iran.

                                       You play his cat :> Trailer  [free]

Continuity - Minimalistic and challenging. Trailer  [free]

Today I Die - poetically sad video game. Play it for free here 

Feign - A game which aims at your space perception.  "Find 9 bodies" - that's a good start. [free]