One of the cutest-looking games that I saw at PAX Prime was Uber Entertainment's Toy Rush. Don't let the cuteness deceive you, though. Toy Rush is shaping up to be a surprisingly deep and fun title.
The developers most often recognized for Monday Night Combat put a bit of a twist on what they know the best. Toy Rush is a tower defense title that tasks the player with focusing on an offensive or defensive approach depending on whether engaged in single- or multiplayer.
Actually, single-player could probably be considered a training grounds of sorts for the multiplayer. The 50 level single-player campaign is oriented around working your way toward destroying the enemy's base by strategically releasing your different foot soldiers. Each level completed earns you tickets, which in turn are used to buy booster packs of cards.