You are basically equipped with some vacuum cleaner given to you by Professor Egads to bust some ghosts. You go into some room, knock on things, basically looking for ghosts. You use your flashlight to reveal their weaknesses and then you vacuum them up. Vacuuming isn't easy cause you have to toggle your joystick to get them in there which can be frustrating yet fun at the same time.
But what's great about this game is the creepy atmosphere which is weird considering this is in the Mario universe. Some of the ghosts are downright scary, at least for kids or kids at heart, but the imagination that is put into them are downright clever.
I also loved some of the boss encounters, as well. My favorite and perhaps the most memorable was the first boss which is essentially this big baby. I don't know why but it always stuck out in my mind.
Luckily, Nintendo isn't letting Luigi's Mansion fade into obscurity as they featured it in both their Super Mario Galaxy games and in Super Smash Bros Brawl. I, like many other people, is hoping for a sequel. The Wii would be a perfect fit for a Luigi's Mansion sequel and hopefully Nintendo is considering on releasing one. Just please, for the love of God, give Luigi a girlfriend or at least a love interest!
Unless you're trying to tell us something, Nintendo.