Titanfall is easily the Xbox One's biggest upcoming exclusive, promising to blow traditional FPS multiplayer wide open with massive mechs, parkour and story context in every battle. If you're in the market for a pre-order, Zavvi are currently offering a 10% discount and £4.50 saving with their PRE10 voucher code (likely to be much cheaper than a new copy at launch).
Mind you, I must point out that Zavvi (and The Hut) are famously bad at delivering pre-orders on launch day. Don't say we didn't warn you. Thanks to dealhunter1233 @ HUKD!