This is also free via the Steam store until 5/23, too:
(When you click on the link it'll say 100% off)
Guacamelee 2 is also heavily discounted. Never played that one, so I bit. The first game is a total blast. I played it on the PS Vita and this version feels a lot bigger than I recall. I think the Super Turbo DLC stuff really fleshes things out.