There have been a lot. I think I've tested more than I can remember, but here are the ones I've actually ended up playing and/or currently testing.
Just posting the online games. Too many offline ones to list.
Magestorm
Air Warrior 3
Everquest 1 & 2
Anarchy Online
World War II Online
Dark Age of Camelot
Horizon
Shadowbane
Global Agenda
Ark:Survival Evolved
Archeage
Tera
Aion
City of Heroes
Champions Online
Neverwinter
D&D Online
Lords of the Ring
Eve Online
Star Citizen
Guild Wars 1 & 2
Star Wars Galaxies
Star Wars The Old Republic
Star Trek Online
Ultima Online
Elder Scrolls Online
Overwatch
World of Warcraft
Elite: Dangerous
Final Fantasy XIV
Dual Universe pre-alpha
No Man's Sky Next
Black Desert Online
Fallout Earth
Defiance
Defiance 2050
Rift
Bless Online
Camelot Unchained current beta
Wildstar
Lineage 2
Tabula Rasa
Forsaken World
Perfect World Online
Silk Road
9 Dragons
Shaiya
Face of Mankind
APB: Reloaded