Ziggurat is a really fun indie game. It's a rogue-lite shooter that harks back to magic FPSes of the 90s, and is a room clearing game like the Binding of Isaac and those FPSes.
It's pretty fun and short, the secrets are neat, the bosses are challenging and visceral instead of overly scripted and overanimated, there's a ton of variety in player classes and weapon types, there are four ammo pools for the weapons which allows for some nice Halo style decisions on what to pick up and drop and what to use for a particular room.