Hard choice, my favourite multiplayer is either Super Smash Bros Melee (can't say brawl cuz it ain't out yet) or Crash team racing (on the playstation 1, not the tag team one). But my fav rpg is either Legend of Zelda Link to the Past, Baldur's Gate 2, or, Samus games. My fav strategy is Age of Mythology, it's just sooo good, and smashes Warcraft in the face. Warcraft is annoying on multiplayer, there's no continuous source of gold, so the aim of the game is to be the last one to lose all your gold. :S Shooters aren't my cuppa tea tbh, although, Halo 3 is good multiplayer, especially Zombie.
star craft all the C&Cs starwars empire at war battlefield 2 Vietnam and 2142 and counterstrike those are my favorites im not really into half life but it has a killer online play
To many to choose from but if I had to choose I'de say the Half-Life Series. I've never been more submerged into a Storyline in my life and the games never get old. Theres so much you can mess around with and over 1000 Mods some mods turning into some of the greatest games ( Counter-Strike, Team Fortress, Portal, Left4Dead, GarrysMod ) If you havent already then I can't recommend it enough but play the games