The award for 'most beautiful game that came out of nowhere' goes to Tokyo 42 [official site]. Mode 7, creators of Frozen Synapse and its ultra-exciting upcoming sequel, will be publishing the game and have just released a trailer. Think Syndicate with a dash of Hotline Miami and a dollop of Big Hero 6's fantastically colourful cityscape. It's an isometric shooter with stealth and open world elements and it's ruddy gorgeous.
Look at it! You probably are looking at it but look harder. In fact, stop reading this right now and plant the entirety of your attention on that trailer.
It's a looker and no mistake. I'm a big fan of the music as well.
As for how it will play, given that it's not due for release until 2017, I think the trailer gives us a pretty good idea of what to expect. Isometric action, with stealth in the form of hiding in crowds and ducking behind walls. The screenshot above is taken from a multiplayer level, which takes place in "hyper-detailed little arenas", whereas singleplayer takes place in an open world city.
More details when we have them.