Co-Op Game
These are the two ones that I've done Co-op in the past, I highly recommend these ones!
**The Adventures of Cookie & Cream ** - https://www.speedrun.com/The_Adventures_of_Cookie_and_Cream Never Alone - https://www.speedrun.com/neveralone
Edited by the author
I am currently practicing Portal 2 with a friend. I can recommend it! https://www.speedrun.com/Portal_2#Cooperative_Game