Duke nukem 64 has some fantastic multiplayer and the good news is that the single player experience is also great.
Although the single payer campaign makes no sense, you play as Duke nukem, a wisecracking guy who gets to shoot up tons of enemies in this game, although the shooting mechanics can be interesting, such as the shrinker.
The campaign isn't necessarily fantastic, but it can be played in co-op and there's some great fun to be found, although the multiplayer is where the game really shines.
You can play lots of different modes, although I really found the deathmatching to be the best since the maps are in pretty much every level of the campaign, although there's a few new ones thrown in for good use. It really is a marvel at how many maps, weapons, and fun can be had, even years after it's release.
The graphics really aren't that great, although everything is detailed, most of it's in low res, still it has a great look to it and there's so many fast paced moments that you really won't notice it to much. The audio department is a bit different though, I really didnt' care for the generic music, but the weapon sounds were spot on and the funny voice acting from Duke nukem is fantastic.
Duke nukem 64 might not be the flashiest title, but the multiplayer far surpasses every other N 64 title, except maybe Goldeneye 007 or Perfect dark. If you like multiplayer games, then definitly check out this game.