I did a review on the indie game Firewatch many moons ago. Over the Christmas period, I had some time to kill in between drinking Scotch and eating ever more tasteless turkey. To my delight, this coincided rather conveniently with the Steam winter sale and I soon spent way too much on many game that I'll never play.
One of the few that I have played is SUPERHOT, another indie game. It's available on all the usual platforms; Windows, Mac and Linux. Looking at the images on the Steam Store page, it looks like a low graphics, basic shooter. In fact it's far more like a puzzle game and the low graphics are quire endearing. The basic premise of SUPERHOT is that "time only moves when you do". This isn't strictly true; it moves at normal speed when you do and very, very slowly when you don't. I found this out the hard way when I went to get a cup of tea in the middle of a level (the autosave is a bit ropey). There are no ammo or health packs; if you're hit once, you're dead and if your weapon is out of ammo, all you can do is throw it. Each level consists on multiple targets that you have to take out with a few basic weapons, some firearms and some melee. Because time stands still with you, it allows you to assess the situation and allows you to piece together way of competing the level in the best possible way. When you've finished the level, it is replayed at full speed. This gimmick is actually quite cool because it shows you how hard it would have been if you'd have had no thinking time. On the theme of difficulty, the game can get quite tricky. There's a particular level when you start in a lift (elevator) with 3 guys pointing guns at you that took me many attempts with trial and error being the only strategy. There is some back story to the game, but it's quite weak and doesn't tie the levels together at all. But that doesn't really matter - think Portal 1.
All in all, it's a great game that'll give you about 4 hours of game play. That was worth it for the small price I got it in the sale for. It's now back to its base price of £17.99 (in the UK obviously). While that might sound like a lot for only 4 hours game play, remember that this is about supporting and indie development team who made an effort to get the game on Linux (I know that Unity makes that very easy, but still), so I'd still recommend you go try it out!