Games currently compatible include:
A Kingdom for Keflings
A World of Keflings
Alien Hominid HD
Banjo-Kazooie
Banjo-Tooie
BattleBlock Theater
Defense Grid
Gears of War
Gears of War 2*
Gears of War 3*
Gears of War: Judgement*
Geometry Wars Evolved
Hexic HD
Jetpac Refuelled
Kameo
Mass Effect
N+
Perfect Dark
Perfect Dark Zero
Small Arms
Super Meat Boy
Toy Soldiers
Toy Soldiers: Cold War
Viva Piñata
Viva Piñata: TIP
Zuma
Love how theres not one Halo game on there.
It looks like they also added Worms 2: A
http://www.xbox.com/en-US/xbox-one/backward-compatibility