Defense Grid - The Awakening

[loop2kil]

Probably the best tower defense game I've played to date...it's not free but worth the $10. A little better graphics than the web based games I've played in the past, on par with the C&C generals era maybe a bit better. It was challenging but not impossible...a couple maps I completed on my first attempt but there were several that required a few attempts

http://store.steampowered.com/app/18500/

[loop2kil]

After attaining the 'Master Strategist Achievement' in this game, I feel like there should be a parade or something....maybe pie