Hotline Miami, in my opinion, is the centerpiece of this bundle. It's about storming a building and killing all of the occupants in interesting ways. It channels this weird 80s rave aesthetic and feels like something between an arcade game, a puzzler, and an action movie. The art uses low-res 2D graphics in a way that's distinct from the usual "8-bit emulation" style, focusing instead on small details. The gameplay complements the art/sound/story elements, and somehow manages to convey more violence than I felt playing Gears of War. I mentioned a story -- it's pretty good, I think, although it's not really the main attraction of the game. Hotline Miami is a game that works very hard to make you feel like you're part of the universe, and, for me, that definitely paid off.
Little Inferno is lots of fun, and casual enough that you can play it in little bites sometimes. If you're going to play it (and you should!), I would not recommend reading past this point. I really like Kyle Gabler's description that "Little Inferno is a quiet introverted art project masquerading as a loud extroverted shopping game." It's fun (although not really challenging or game-y, not that it's designed to be) at first, and then pulls you into its story very effectively. The result is that I didn't notice that my little casual play session had turned into a kind of desperate dash to unlock the next tidbit of story until the game commented on it. It plays on your feelings very well, and the ending is up there with Portal as far as innovation and poignancy are concerned. Both Little Inferno and Hotline Miami gave me trouble sleeping the days after I finished the game, and that's a good thing.
Awesomenauts is like DotA, but 2D and simpler. The graphics look a little childish, but that belies the tightness with which everything handles. It's well made, and fun for the occasional bout of competitive play, especially if you don't have the time/nerves to get good at DotA/LoL like me. That said, I don't find myself playing it very often, although that's probably more because of me than because of the game. Oh -- and it has microtransactions, but they're well-managed and totally optional.