A little trick when looking for something on Mobygames...
 

If you append these to a Game Browser URL, you can add one extra filter where normally it would not be applicable. (eg, you can search for games associated with two genres) :)

There are more than these, but not all of them HAVE associated games.
Only one each of e, f, or x can be used at a time.

Alphabetized list:
1st-Person Perspective: x,7
3rd-Person Perspective: x,16
Action: x,1
Add-on: x,62
Adult: x,87
Adventure: x,2
Anime / Manga: x,57
Arcade: x,9
Baseball: x,32
Basketball: x,33
BattleMech: x,72
Bike/Bicycling: e,104
Bike/Bicycling: x,104
Board / Party Game: x,26
Bowling: x,88
Boxing: x,36
Cards: x,27
Casino: x,28
Chess: x,11
Coin-Op Conversion: x,10
Comics: x,68
Compilation / Shovelware: x,76
Cricket: x,73
Cyberpunk / Dark Sci-Fi: x,66
Detective / Mystery: x,55
Ecology / Nature: x,81
Editor / Construction Set: x,42
Educational: x,12
Emulator: x,90
Fighting: x,48
Fishing: x,18
Flight: x,19
Football (American): x,31
Foreign Language: x,85
Game Show: x,29
Geography: x,71
Golf: x,35
Graphics / Art: x,79
Health / Nutrition: x,92
Helicopter: x,56
Historical Battle: x,14
History: x,74
Hockey: x,34
Horror: x,83
Horse / Derby: x,91
Hunting: x,61
Interactive Fiction with Graphics: x,24
Interactive Fiction: x,23
Interactive Movie: x,60
Isometric: x,25
Licensed Title: x,82
Managerial: x,40
Martial Arts: x,39
Math / Logic: x,43
Medieval / Fantasy: x,78
Meditative / Zen: x,69
Mental training: x,107
Motorcycle: x,20
Music: x,59
Naval: x,41
Off-Road / Monster Truck: x,58
Olympiad: x,38
Paddle / Pong: x,64
Paintball: x,105
Persistent Universe: x,94
Pinball: x,53
Ping Pong/Table Tennis: e,103
Ping Pong/Table Tennis: x,103
Platform: x,21
Pool / Snooker: x,89
Post-Apocalyptic: x,65
Pre-school / Toddler: x,46
Puzzle-Solving: x,30
Racing / Driving: x,6
Reading / Writing: x,44
Real-Time: x,15
Religion: x,84
Rhythm / Music: x,97
Role-Playing (RPG): x,50
Rugby: x,75
Sailing / Boating: x,63
Sci-Fi / Futuristic: x,8
Science: x,86
Shooter: x,22
Side-Scrolling: x,17
Simulation: x,3
Skateboarding: x,52
Snowboarding / Skiing: x,95
Soccer / Football (European): x,49
Sociology: x,98
Sports: x,5
Spy / Espionage: x,93
Stealth: x,99
Strategy: x,4
Surfing: x,109
Survival Horror: f,102
Survival Horror: x,102
Tank: x,80
Tennis: x,37
Top-Down: x,13
Train: x,108
Tricks / Stunts: x,96
Turn Based: f,106
Turn Based: x,106
Typing: x,45
Video Backdrop: x,67
Visual Novel: x,111
Volleyball: x,77
Wakeboarding: x,110
Wrestling: x,51

Thank you very much! :OK: I'm addicted to that database :drool:
I've proposed several fixed on MobyGames forums and bombarded their staff with PMs, I don't care about the latest trends in GUI, but more search options are a must for data mining.
Thanks to your tip I've managed to do a following trick:

if one of the options mentioned above is on this list (unfortunately not all are) you can mix even two options, like this!

Example: a wonderful listing for wargamers

Haha, this is loveable! ^_^ Thanks for the info!