If you pre-purchase Shadowgrounds Survivor on Steam you will get the original Shadowgrounds game for free.
The new expansion costs just USD 19.95 (GBP 9.60) and adds lots of fancy bits and pieces to Frozenbyte's top-down alien shooter.
There are three new characters each sporting new tactics, a new RPG-like weapon upgrade system, Sentry Turrets and Mechs, new graphical polish, better physics, an editor and two new modes.
The Campaign mode is based around the trio of survivors joining up with the rest of human kind to battle the nasty and non-negotiable aliens, while Survival mode throws wave upon wave of enemies on you and simply challenges you not to be eaten or ripped to pieces or strangled or whatever nasty UFO thing wants to do to you.
Shadowgrounds was released in 2006 to average applause. Pop over to our review to find out more.