Defense Games

Since I generally hate on the genre as a whole, while every now and then saying "this is one of a select few defense games I actually like", I figured maybe I should list the ones I do like and maybe say a bit about why I like each one.  Also, links to where each game can be played or otherwise obtained, for your convenience.

Plants vs. Zombies (demo available) - It's a rather novel concept of plants as your weaponry to kill zombies.  The game has a great sense of humor and offers a lot to do within its design and mechanics, including a minigame where you get to play as the zombies.  I actually like the Xbox 360 version a little more, because it has co-op.  It's a little low on the replay value, but then again most defense games are.

The Arrow of Time - You're shooting arrows at things.  As you progress you can unlock and upgrade different types of arrows and even combine two types into one arrow, allowing you to make a variety of different combinations.  The music really adds a lot to this one, especially once you realize it's the same song in each area, with a different style representative of the time period.  The music geek in me really loves the different interpretations of the same melody.  The game itself is kind of short, but if you feel like clicking madly for a while, give it a go.  My personal recommendation is the combination of homing and piercing arrows.

Shopping City - This game where you have to put up stores to drain peoples' wallets is a defense game in disguise.  Their wallets are essentially their health bar, and you need all the money you can get to build more buildings and get upgrades in later levels.

Dungeon Defenders (demo available) - Just the right mix of defense and role-playing.  As you level up you can distribute points into various stats that control various aspects of each of your defenses, or boost your own stats, or even give yourself special abilities.  Also, you have equipment, including weapons, and can run around beating the crap out of things.  I played a few levels solo during a Steam free weekend a while back, but it's really a multiplayer game.

Yeah... only four to date.  I should mention that I was vaguely interested in the combination FPS/Tower Defense game Sanctum, but have never actually played it.  There is a demo available, though.