Luigi's Mansion is one of the most under-rated games of all time.
This is Luigi's first game dedicated entirely to him. Prior to this he had always been in Mario's shadow. He was Player 2, a mere Mario pallette swap. But in this game we get to see who Luigi REALLY is. So for a guy who's always been a secondary character in a Mario game, it's really shocking how unlike a Mario game Luigi's Mansion really is. There's really nothing like it. Luigi's goal is to save Mario from the evil King Boo--a ghost who captured Mario through means I don't feel like explaining. There's two problems: Mario is hidden in a haunted mansion. And Luigi is a friggin' coward. Armed with a shoddy vaccum cleaner-type device, you must rid the haunted rooms of the Mansion from ghosts, collect keys, solve puzzles, defeat bosses and hopefully save the day. This may sound really generic, but it really plays like nothing else out there.
For one thing, the vaccum-cleaner--cleverly titled the Polturgust 3000--is a masterful creation by Nintendo in of itself. This is the main gameplay mechanic; you'll use it to suck up ghosts, and shoot water and fire at some of the tougher enemies. And damn it if it isn't a crapload of fun to use. It's really a showpiece of how well designed the Gamecube controller is. Sucking up ghosts is a true joy--thank goodness, because that's what the entire game revolves around.
It also feels more like a Zelda game than a Mario game. The entire game takes place inside the titular Mansion, which is wonderfully elaborate and intracate in its design. You'll clear rooms full of ghosts in order to get a small key, which will unlock another door to the mansion, etc. It's sort of like one gigantic Zelda dungeon. Except creepier. In stark contrast to the happy-go-lucky, bright and colorful, "Whoopee!" Mario games, Luigi's Mansion is an incredibly dark and creepy afair. There's some genuinely chilling moments in this game; despite its E rating, I certainly wouldn't recommend it to younger children.
Luigi's Manison was technologically incredible for its time, and it still impresses today. Luigi himself is very expressive and full of life. You can see his teeth chatter and eyes shift in fear. He'll even whistle along to the theme song when things get eerilly quiet. One of your main tools in the game is the flashlight, and the lighting effects in the game are still stunning to this day. Equally amazing is how realistically the Polturgust 3000 interacts with its environment.
The game is very short, and there's very little replay value. But other than that, I have very few complaints about Luigi's Mansion. It's one of my personal all-time favorites, and a must have for any Nintendo fan.