Besides Gates of Osiris, the guys at Fenix Fire also showed a free-to play action game called Smash Derby at GDC 2014. This light and fast title pits players in a gritty arena full of orange and blue robots. Tap your own bot to switch colors, so you can successfully bash into same-colored mechs with a quick swipe. It's a battle against the clock to wipe out the other bots while making sure you don't accidentally bump into those of opposing color. Between rounds, you have the opportunity to drop defensive structures around the stage and take on the next batch of would-be robo-champions.
From the bit we've seen, Smash Derby looks fun and fluid. It should be out some time next month on Google Play first (don't let the iPhone demo device fool you) and Ouya, with other platforms like iOS, Windows Phone and maybe even BlackBerry due afterwards thanks to easy exporting through Unity. More info and screenshots can be found at the Fenix Fire site.