The most recent Team Fortress 2 update (which comes with awesome
comics) pits a group of six human players against wave after wave of killbots. You get to buy upgrades and utterly wreck metal dudes. It is a tremendously fun introduction (or re-introduction) to the game, which is 100% free to play on Steam.
I'll be looking for people to play with, probably tonight. Am willing to walk through the basics for completely new players. Poke me if interested! Steam name is Squinkypoo.