Turretmaster by Hikati Games
A war torn future where one mechanic defends the towns from an invading army of mind controlled soldiers. Use Lasers, Missiles, Fire and of course good old fashioned Shells to tear apart the enemies on both land and air, get gold from your kills to upgrade your arsenal.
Play through a campaign and try to rank on the leaderboards, which are specially created to track skill. There are a finite amount of points you can get on a given round and the cap is extremely high to reach and requires expert level playing. See if you can reach the top spot.
Become a creator and design your own campaigns with the in-depth level editor. Edit everything from how many units per wave and per round to what weapons the player has access to. Use your custom campaigns to test the mettle of would be teammates, for those who reach the top of the leaderboard truly earned it.