Tower Defense has somehow become its own genre lately, and what an addicting genre it is. The games center around preventing enemies, or creeps, from traveling from thier source/spawnpoint to your sink/base by building upgradable, stationary attack towers. They also tend to have a terrific sense of flow, as it’s all you can do to keep up with the never-ending waves of enemies while building up your defenses. Because of the hightened sense of flow it’s easy to waste hours upon hours playing them, so be careful with this one.
You see, GemCraft is a highly polished TD game with distinct stages, a “level up” mechanic for improving your stats, and a much needed save function as the game is easily several hours long even if you’re good. The most interesting thing though is the importance of color. All weapons (gems) in the game have a hue value, and gems are especially effective against enemies of opposite hue. So an orange gem works well on blue enemies, and a green gem works nicely on red creeps. The game gets really good when you start “mixing” gems to make them more powerful and combine colors, bonus stats, and of course change the hue value. It’s hard to explain, but great once you start playing.
Be warned, the game is highly addictive.