In no particular order:
PSO(DC): I had a Ranger around level 70, then my DC was stolen along with all the games. Picked up another DC and PSO and created a Fonewm and leveled it up to around Lv. 33. Later picked up Ver.2 and created a HUmar and leveled it up to around Lv. 33 as well.
Ms. Pac-Man: I've played so many versions of this game, that I have no idea how many hours I've put into it. So simple, yet such a well designed game. Versions played: C-64, Arcade, Atari 2600, PSX, DC and Atari Lynx.
Combat (Arcade, 2600) : I played the arcade version at the Roller Rink every Friday (If that does'nt tell my age. :D ), but it was'nt until my parents bought the family an Atari 2600, that I wore this game out. My family hated playing against me on this game, as I could hit any shot, from any angle on a whim. I'd play different levels of the game, to increase my personnal scores. It was the only game we had for the system, the first year.
Space Invaders(Arcade, 2600): Played the arcade version at the local bowling Alley for the first year or 2, then our family got it for the 2600. As with Combat above, it was the only game we got for the system that year. I was pretty much a master of this game. I could flip the score multiple times and could nearly flip the score playing the invisible game. I fired up the old 2600 last year and still was able to run through the game like it was yesterday.
Daytona (Arcade, Saturn, Dreamcast): I had put quite a few tokens in the old arcade unit, but when the Saturn version finally came home, I played it everyday for the first 3 months. I later purchased C.E. and amassed quite a few hours into it as well. Then the DC version came out and I played the home and online versions here and there.
Donkey Kong (Arcade, 2600, Colecovision, Intelevision and C-64): When this game arrived in arcades, I was hooked. Never had an arcade game looked so good and the simple yet addictive level design had not been as well done, since Pac-man/Ms. Pac-man. I liked the game so much in the arcade, that I spent a good portion of the $18 I had playing this game. By today's price standards, that would be like spending near $100 at the arcade. Later on, my neighbor lent me the Atari 2600 version that I played everyday after school for a month solid. My other neighbor had an Intellevision, which I'd play Donkey Kong on, every time I went over. Another friend had a Colecovision, with at the time, the closest version of Donkey Kong available in the home. I later discovered the C-64 and aquired a bootleg copy of 10 arcade hits. Donkey Kong was one of them and to my surprise, it was the best home version ever.
Street Fighter II (Arcade, SNES, Saturn): Between the original and Turbo/Hyper Fighting, this has to be the one fighting game, that has never grown dull. It is the perfect example of 2-D fighter games.
Missile Command (Arcade, Amiga, C-64, 2600, compilations): Atari sure knew how to make arcade games that had an addicting hook and this title was one of them. I played the arcade game every Friday, until my parents finally got it for the Atari 2600. Since we had so few titles for the 2600, I played this game like a mad-man for a good year solid. I actually have it in my current play list, through the Atari Anniversary collection on the DC.
Asteroids (Arcade, Atari 2600, compilations): Such a simple design, but it just had that gaming hitch (Atari's greatest days in the arcade) that so many Atari arcade titles had in that day. I played the arcade game where ever it was available. The game was so popular, that you'd find it at the local grocery store. My parents picked it up for the 2600, the same year as Missile Command. It was sort of a letdown on the 2600, but that did'nt stop me from enjoying what it had to offer.
Phantasy Star II : It was the first game I had on my Genesis, along with Altered Beast and Super THunder Blade. I played through the game within a month of owning the system and later played through the game a couple of years later. When I bought a Nomad, I played about a 3rd of the way through the game again. I really loved the music soundtrack to this game and it set the mood perfectly.
Super Mario: Who has'nt owned a Nintendo Entertainment System and not played this game to death. It was the very reason I bought the console.
Honorable mention to: PSI-5 Trading Post(C-64), Phantasy (C-64), Galaga, Summer Games (C-64), Sega Rally 95 (Saturn), Galactic Attack and Last Gladiators(Saturn), as any one of these titles could fit in the list as well.
