I'm hanging out with my buddies this weekend and there will be 8 of us in a house so I had the grand idea to see how many games on the Xbox One list are multiplayer. I'm sharing this list with you guys as it might help people plan a little LAN party. These are all taken directly from their store page which list Local/Online coop player numbers. I also didn't check any of the Xbox 360 games which is probably a huge disservice, except for Dungeons & Dragons. I have memories of that, an Action RPG in the arcade?!
Also, if you have 2 Xboxes I'm assuming you can game share the service so if it says Online, you can probably (I haven't checked) run something like Terraria and put 4 people x 2 consoles and everyone join the same game making for a grand total of 8 players.
2-Players
Dungeons & Dragons: Chronicles of Mystara 2 Local - 8 Online (I thought this was 4player Coop?)
Gears of War: Ultimate Edition - Day One Version 2 Local - 8 Online
Blood Bowl 2 - 2 Local
Defense Grid 2 - 2 Local
4-Players
Super Mega Baseball: Extra Innings - 4 Local
Mega Coin Squad - 4 Local
NBA 2K16 - 4 Local - 10 Online (I'm guessing this is 3 Xboxes if you wanted to play in the same game together of 4+4+1 players per team)
The Golf Club - 4 Local
Terraria - 4 Local - 8 Online
6-Players
WWE 2K16 - 6 Local
8-Players
#IDARB - 8 Local/Online
Knight Squad - 8 Local/Online