Into the Breach is a simple indie turn-based tactical combat roguelike from the makers of FTL, where you pit giant mechs against giant bugs. Well, simple in the same way chess is simple - the basic mechanics of seeing what the enemies are going to do and using your turn to damage or move them so they don't damage you and your buildings are simple to learn and hard to master.

I've already written a bit about it in this post which talks about how you can play it on mobile as part of a Netflix subscription, if you like games where you can take your time to think of the perfect move then this is probably your cup of tea. Also since I first played it they've added a big free expansion including a difficulty called "unfair", so that's what's keeping me busy at the moment.