A tower defence style game with many different types of turrets, combos, upgrades, enemies, maps and lots, lots more. Map editor, modding interface, challenges, the list goes on. Full instructions can be found by playing the in-game tutorial or by checking out:
http://onslaught.playr.co.uk/about.html
Spiel Tags
combo, creep, onslaught, Tower Defence, turret, Tutorial, wave