There's been a few. Lets see what I can dredge up from my seedy past...
Golden Axe
I think this was on a 386. Possibly a commodore. It was a side screen scrolling adventure game. You could use a Warrior, Dwarf or Amazon. Two people could also muliplay on the same keyboard. Very addictive, and had that trait of games from that era of being so damn hard end game. Great music
Wing Commander
Pretty sure this was on the 486. A great space flight sim game. Had the coolest mothership ever, the Concordia. Can't remember the name of the enemy, but they were basically walking Tigers.
Orion
I dont think I have ever replayed a game as much as Orion:Master of Planets. A turn based space strategy game, where you could pick different races, each with different traits. Whocan forget land based invasions, your troops lined up like dominos, and then exploding like little cap guns as they died. It was like civ with space ships. Which leads me neatly to...
Civilization(1&2)
Follows Orion as most replay value. I am a bit vague on 1, but 2 is crystal clear in my mind. Every strategy gamer here probably has an upbringing on some of the Civ franchise. I would even hazard a guess that many games of that era took entire pages out of the civ book. Flat 2D terrain, with little paper representation of units never looked so good. Flattening the entire world under your Roman boots never felt so good. We found out later that editing a config file aloud multiplay on the same computer, but made the game crash if you had an audience with each other.
Planets
The 386. A bit like Orion, but more expansion orientated, probably had more in relation to Sim city really. Had more micro managment. Its main attraction was that the traits of the races really were very different to each other. At the end of the turn, you had to load up the Command line, and compile each turn. Having three people clustered around the screen waiting for the line:
EVENT: Battle between [gary-green giants] and [Kevin - Plundering Virgins] was always exceptional.
Goldeneye
Ok, going on the consoles with the Nintendo 64 (a great gaming console, that was limited by just that.... consoles, making it lose the war to the PS1 with its CD media) GE was a terrific game, definitly the flagship of both Rare (who went on to release the acclaimed Perfect Dark) and the N64 itself. Had so many challanges to do, great 4-way muliplayer with great sub games (Pistols, License to Kill, Facility - Best ever) Each of the 21 levels had 3 difficulties. When these were complete, it unlocked a special setting, allowing you to set the health,speed and accuracy of the AI. Throw in time trials for cheats, and you had a great, great game.
Monkey Island
Anyone remember the rediculous page wheel you had have, so you could correctly identify the required symbol to launch the game. Barring that, a game with amazing mood and setting. And had terrific puzzles and storyline. With an absurd learning curve, this was a frustrating, yet strangly rewarding game.
Paperboy
Back in the days of the Amiga 500 (which was an awesome piece of kit for its day). This simple but adictive game, had you throwing out newspapers to fend off dogs, going up streets for side quests. Was one of those games that never ever finished.
Im sure im forgetting some, but I'll come back to this list if I think of them.