I try to do 1 of these a year so here is my list of things im waiting on.
Last year I said I can't wait for "Counter Strike Global Offensive". I love the game and am watching the finals of IEM right now on Twitch. I was in the beta but since I don't have a Windows partition since last year I couldn't play it or some other really good games that I am waiting on. Any time now Valve :-/ (side note as of this post its on sale so if you like FPS games and have a computer made in the past 2 years id suggest picking it up)
"Wasteland2" is something im definitely looking forward to playing. I played Fallout1 and my turn based story itch is getting to me since its definitely not a popular genre of games any more the space is definitely there for a game like this. Its already on steam in early access but not out on Linux yet but since its written in Unity3d it is only a matter of time before its out but ill wait to buy it myself, it seems like it will be on Linux in a few weeks given it was just released on MacOS. Side note they also have another game in development called torment tides of numenera which sounds like it won't be out till next year but it looks like a good game too.
"Planetary Annihilation", its a super strange thing to be excited for a game that I already have in my library but im still waiting to actually play it more since last time I had the chance was late alpha. I recently got an AMD R9270x and the game sadly doesn't work correctly on my machine. The even more frustrating part is I was using haswell graphics before that and they didn't work with it either. So I really hope their support gets better so I can actually play it some more but if you have Nvidia hardware go right ahead and play yourself if you like RTS games. This has a really fresh take on the genre of RTS.
"Prison architect", wow what a game for something so cheap and such a simple idea. Make a prison and keep the prisoners in there. The game is in early access as well like wasteland and planetary annihilation but is very stable and they are adding new things every month. Its really great to play a game that isn't finished and yet you can sink hours into it and make amazing things, then come back the next month and see whats changed. Go out and get it if you want something to relax and have fun and watch the rioting, fires, escapes and general mayhem that happens. I wouldn't say it would be the greatest game for kids or anything but about 15-50 should get a good laugh from it.
And the last game is "Castle Story", its a pretty simple game kind of along the line of minecraft but its like an RTS mixed with tower defense. I really enjoyed the survival mode a lot and its really cool in general.