For me, this year's best surprise has been For Honor, a game that seemingly crushes together Dynasty Warriors' army-on-army scale, Bushido Blade's punishing swordplay and Dark Souls' PvP emotes - all within the familiar mould of the online shooter. Also, it's about Vikings killing Samurai killing Knights. It looks wonderful.
Yesterday's reveal gave some sense of the game, but Ubisoft's snuck out a gameplay walkthrough. It covers a single 4 on 4 Domination match, explaining the concept, the combat (particularly the difference between Creeps and Heroes) and the flow of a full game.
I'm particularly fond of the reckless disregard for history, extending all the way to including fancy medieval banners with big letters on them to signify control points. Magic.