A roleplaying system which may have some serious appeal for those looking for old school thrills and monster bashing is Ancient Odysseys: Treasure Awaits! Two releases are currently available through DriveThruRPG with the core set as well as a supplement available to bring more action to the gaming table.
From Precis Intermedia:
Treasure Awaits! is the award-winning retro-style fantasy roleplaying game that is perfect for beginners and veteran gamers alike. Dungeon-crawls have never been like this, as the game supports GM-less, solo, and traditional gamemaster play. Quick and easy conflict resolution requires only a six-sided die. Experience perilous traps, vicious monsters, toxic poisons, powerful magics, and valuable treasures in an affordable package. It’s retro, but not a clone.
More Treasure Awaits! adds new options for play to unleash even more of your imagination… pious clerics and resourceful pathfinders join mighty warriors, powerful wizards, and crafty rogues. Their exploits are no longer limited to ancient dungeons and catacombs, as they venture through the wild landscapes of the surface, and face the crime and trade of towns.