For anyone interested in a cool tower-defense style arcade game, I recommend checking out Toy Soldiers. (Xbox 360 only, sadly.) I picked it up last week when it was on sale for $10, and I've gotten more hours of fun out of that 10 bucks than I did out of the $60 I spent on Halo: Reach. 
The game concept is basically WWI battles fought with (you guessed it) toy soldiers. You play the British or German armies. I'm not usually one for tower defense games, but this one mixes up the formula a bit by allowing you to take control any emplacement (MG nest, mortar team, howitzer, AA gun, etc) at any time, and giving you different vehicles to drive (tanks) or fly (bi-plane fighters or bombers) so you can take a front-seat role in the battles rather than just building some towers and then watching passively.
You begin every battle mission with a certain amount of starting cash to build up your initial base defenses (like an RTS game), and as you destroy enemy troops and vehicles, you gain money to buy additional defenses or upgrade your current emplacements. You can also earn bonus cash multipliers by taking control of an emplacement or vehicle yourself and destroying enemy assets, which gives you an incentive to take an active role in the battle since doing so earns you more money.
Besides the campaign, there's also a Survival game mode and some multiplayer offerings - 1v1 battles that you can play in split-screen or via Xbox Live. After finishing the base campaign, you also get to play a "Campaign+" mode where you control the German forces and fight through modified versions of the campaign battles from their side.
All in all, I highly recommend it. The graphics are surprisingly detailed, the gameplay is fun and engaging, and the whole game is very polished. For $10 (on sale; $15 normally), you can't go wrong.

The game concept is basically WWI battles fought with (you guessed it) toy soldiers. You play the British or German armies. I'm not usually one for tower defense games, but this one mixes up the formula a bit by allowing you to take control any emplacement (MG nest, mortar team, howitzer, AA gun, etc) at any time, and giving you different vehicles to drive (tanks) or fly (bi-plane fighters or bombers) so you can take a front-seat role in the battles rather than just building some towers and then watching passively.
You begin every battle mission with a certain amount of starting cash to build up your initial base defenses (like an RTS game), and as you destroy enemy troops and vehicles, you gain money to buy additional defenses or upgrade your current emplacements. You can also earn bonus cash multipliers by taking control of an emplacement or vehicle yourself and destroying enemy assets, which gives you an incentive to take an active role in the battle since doing so earns you more money.
Besides the campaign, there's also a Survival game mode and some multiplayer offerings - 1v1 battles that you can play in split-screen or via Xbox Live. After finishing the base campaign, you also get to play a "Campaign+" mode where you control the German forces and fight through modified versions of the campaign battles from their side.
All in all, I highly recommend it. The graphics are surprisingly detailed, the gameplay is fun and engaging, and the whole game is very polished. For $10 (on sale; $15 normally), you can't go wrong.

