What an awesome hidden gem. The location is not too far off-strip, and just a little bit past UNLV. There's a giant sign that tells you it's location.
Inside, it's like a giant pinball arcade. They range from ancient Bally's classics to the modern pinball game you'll see at your local pizza shop. They even had a crane game from the 1930's... which goes to show you how long they've been taking people's money with that damn machine.
There are also some other arcade games scattered about, including some of those old-fashioned shooting gallery games. And the best part of all this is that most (if not all) the games are 25-50 cents a play. And it's pinball, so that single quarter can get you a solid 10-15 minutes of gameplay if you are that lucky/talented.
I'd highly recommend checking this place out if you have a free morning in Vegas. It'll take a cab or bus to get there, but I just drove myself from the strip to the Pinball Hall of Fame and back in time to get lunch at Aria. It's worth the trip if you're a fan of pinball.