I regret paying $5 for Hotline Miami.
Even though I have good eye sight the game's visual design is atrociously hard on the eyes. The main menu is almost illegible, it has zero options for resolution or anything else, has weird horizontal lines across the actual game like its taking place on a old monitor and I am frequently killed by enemies from off screen.
Besides that it is a fun game, and the music is good, but the above really doesn't make me want to keep playing.
I also picked up Sword of the Stars II for $4.74 from GamersGate, excellent purchase, beautiful and detailed game, quite deep and all the planets have santa hats ^_^