I'll just categorize them, like TimovieMan
Platformers:
Besides adventure and strategies, my fav genre
Pitfall: The Mayan Adventure - great, great game that i first played on my Sega Mega Drive 2. It's a pure action game but there was something really "adventurous" about it with "Indiana Jones" feel to it that it still remains one of my fav games. The animations of the character and response to controls are marvelous, which as for me is the most important factor for these sort of games.
Aladdin - another great platformer/action. Even today, when i don't know what to play i would gladly turn this little gem on, as i'm also a sucker of Disney animated movies.
Hercules - speaking of which, another of my favs
Trine - wonderful game in a "retro" style, with a really nice music. The "physics" aspect is also neatly done and quite original.
Multigenre:
These are the games i especially admire, and even they can often hardly satisfy lovers of individual genre, i thought the authors always deserve respect when they try to make something like this.
Defender of the Crown - what to say, one of the first games i ever saw, on my friend PC. The remake wasn't bad, too.
Conqueror A.D. 1086 - game which is strategy, RPG, action, adventure... Not a perfect game, but i had great time with it.
Dragon Lore 2 - less popular Cryo game, which fascinated me at the time with its lush graphics and fantasy setting. Gameplay wasn't that good, but the game had a nice and magical ambience.
Fighting:
Mortal Kombat 1, 2 and 3 - simply the best fighting games
Street Fighter 2 - who can forget it, played it as a child on game machines
Driving:
Ignition - amazing little game! I still play it. Try it if you hadn't!
Shooters:
Blood, Quake 2 and 3 - my first FPS multiplayer experiences
Battlefield - Vietnam and Battlefield 2 specifically. Great multiplayer feeling.
CoD 2 - out of the series, i played and liked this one the most.
Outlaws - i'm sucker for old west. One of the best music in games
Simulation:
I love this genre as well, as i love creativity and historical based games.
Caesar 3 - i love old Rome, this one is still one of the best
Pizza Tycoon - i love pizza!
Gloriana - be a merchant in age of discoveries. I had to use my notebook to write down the prices of goods.
Pirates - i played the remake.
Commandos and
Desperados - hard but fun
Pinballs
Full Tilt! - 1 and 2, it's the pinball which one of tables featured in old Windows.
Strategy
Lords of the Realm 2 - one of the best medieval experiences
C&C Generals: Zero Hour - amazing game, so many possibilities
Stronghold - sweet
HoMM 3 - legendary
RPG
Gothic 2 - great, i played 3rd one a little bit also
Diablo - spent many nights with it
Pirates of the Caribbean - good game, not connected to the movies
Action/adventure
Tomb Raider series - oh come on, we were all amazed by Lara!
Alone in the Dark series - didn't play all of them, but classic horror experience
Time Commando - one of my all-time fav
Adventure
I've already named some of my favs
here so i'll just give a random bunch of it - GK, Broken Sword, Monkey Island, The Longest Journey, The Last Express, Journeyman Project 2 & 3, Keepsake, Phantasmagoria, Ripper, Touche, DoTT, Full Throttle, Flight of the Amazon Queen, Kyrandia...