In no particular order:
Gauntlet/Gauntlet II (original arcade versions)
Street Fighter II (and its many permutations on just as many platforms)
Dungeon Master (Atari ST)
Bard's Tale series
Diablo series
Utopia (Intellivsion )
The Power of He-Man (also Intellivision)
AD&D Treasure of Tarmin/Minotaur (guess what? )
Command & Conquer: Red Alert (the best mix of weapons in the entire series)
The AD&D Gold Box games
There were others, but these were the true time-killers!