Bruh, XB1 has a ton of co-op games that are not online. The arcade titles bruh
Chariot is bomb
Guacamelee: STCE
iDarb
Pool
I believe Max and the Curse of the brotherhood has that
Tale of 2 brothers was free recently if you got a 360, co op
forza horizon 2 (well, I think it has split screen)
COD games have co op
Assassins creed games
Project Spark has a TON of co op games in all categories. hardly talked about on here

coli
Angry Birds star wars (now finally $10 after being $50 for the longest)
Borderlands handsome collection
Castlestorm
Child of light
Dead Rising 3
Dead Island 2
Crimson Dragon does too I'm pretty sure of
Dragon age
Diablo 3
Just Dance
Dance Central
Geometry Wars 3
Happy Wars XB1 version
Farcry 4
Halo Spartan Assuault and the other one
Halo MCC
Plants vs Zombies
Kalimba
All the Lego games
Titanfall has a cool online coop mode they added last October
Sunset Overdrive does as well, 8plyr is their joint
Shiftlings
Zoo Tyc00n
Fruit Ninja Kinect 2