I disagree in that I think it's actually pretty fun 2nd time through with all levelled-up people, but hey, that's just me maybe. Either way, awesome game.
Also the Pixeljunk games, being "Eden" and "Shooter" are awesome. Both have demos, so you'll know fast if you'll like them or not, but I highly recommend them.
Fat Princess is also surprisingly fun. It can be frustrating if the teams are completely unbalanced with skill/initiative, but 90% of the time it's a blast.
Also my wife and a few of my friends are REALLY fond of "Mushroom Wars." It's an RTS-kind-of. Again, try the demo, see what you think. I couldn't get into it, but as I said, a lot of others I know REALLY like it.