Monster Island is a set of tabletop rules for giant monster combat. Grab some toy monster figures off the shelf, use the monster creation rules to design your monster of choice, and then fight it out for supremacy.
This game is very well done and is a great example of the advantages of PDF publishing for niche game products. There are numerous expansions and supplements on the Monster Island site that take the game in pretty much every direction a giant monster game should go — robots, human armies, alien invaders, etc.
Suddenly our launch was swamped by a tremendous wave as a gargantuan form emerged from the deep waters off our starboard. Our cheers were drowned out by the monster’s mighty roar as the reptilian titan glared in disapproval at the shoggoth, even as the horror slithered across the waves. We cheered as Godzilla swam forwards to engage the formless abomination of prehistoric blasphemy. Before the alien horror of the shoggoth, Godzilla was the lesser of evils and we prayed for his victory.