Dungeon Defenders II
I kept seeing a couple of my friends pour hours and hours into this game even though it's only in alpha. I figured there must be something worthwhile here if they're playing it that much.
And there is! It's a fun tower defense and third-person shooter hybrid of a game. It's much improved over the first Dungeon Defenders. It's easier to play and more fun in the moment to moment gameplay.
Right now my main problem is that it's ok with random matchmaking but it would shine with a premade group of four friends over voice chat. And no one else I know owns the game.
I'm guessing hype will rise for this game when it enters beta and then finally releases. This is going to be one that I let sit on the backburner until I see more of my friends pick it up. I can tell that it'll be a lot of fun with a premade group once more people are playing it.