Checking my e-mail... these are the ones Guinness accepted. I don't remember which ones we missed, but some are pretty obvious they can't be done.
First-person shooters
Tactical Shooters
Third Person
2D Shooters
Online Shooters
Rail Shooters
Football
NFL
Baseball
Golf
Tennis
Football
Extreme Sports
Simulation Racing
Arcade Racing
Street Racing
Kart Racing
Mini Games Compilations
Fitness Gaming
Rhythm Games: Karaoke
Rhythm Games: Instrument
Rhythm Games: Dance mat
Open World
Narrative Adventure
Stealth
Survival Horror
2D Platformers
3D Platformers
Point and Click
2D Fighters
3D Fighters
Hack and Slash
Combat Sports
Block puzzles
Spatial Puzzles
Physics-based
Logic Puzzles
Word Puzzles
Japanese RPG
Western RPG
Action RPGs
MMORPG
MMORPG - Social
Turn-based Strategy
Real-time Strategy
Simulation
Classic Arcade
Modern Arcade
In order to qualify, we had to play a genre for at least 5 minutes. Replays could not be done. Playing multiple levels within a genre in order to reach that goal was acceptable. Stuff like MMORPGs and whatnot were a little out of reach and we could not go into create mode and build a stage to fulfill a genre. There were some other stipulations that limited our ability, but if we could've done that, we'd have covered way more ground. We did try to get the community who already had the game to build levels that had the genre we needed and was also multiplayer accessible, but they failed us, lol.