What game and why?   If it is other reasons then post below.  Features, games, developers, brand, price, hardware, etc.

If you won't own it yet, what are you waiting for?

Dead Rising 3.

Also, Quantum Break is a nice, awesome bonus.

There was multiple games that i really wanted but for me to buy it at launch Ryse: Son of Rome sold me. Though i cant wait for TitanFall xD

I'm looking forward to Titanfall and Halo 5. I'm sure there will be a ton of indie and arcade games that come along that I will like. I'm hoping they can breathe life back into the Gears universe, after the lackluster Judgement that was released.

First it was Forza 5 because I'm a big fan of the series

And a lot of the other games it has but especially Sunset Overdrive, I just know it's going to be awesome.

The 360 sold me

Killer Instict, Zoo Tycoon, Dead Rising 3 all sold me. If only one of those was coming at launch I wouldn't be bothering.

Far more excited for Sunset Overdrive, Quantum Break, Titanfall, Garden Warfare and Fable Legends tho.

The entire Exclusive Library that they showed at E3

They system is self is what sold me. Killer Instinct is the game that really got my attention.

Destiny, Halo 5, Titanfall, etc....