Action: Source is a free to play mod for the Source Engine. Action: Source is designed to simulate being in an action movie or what we call Movie Realism. Movie Realism means that you can take a few hits and keep going. You can bleed and break bones, but don't worry you can bandage yourself up. You're an action hero! This doesn't mean you're invincible, headshots can be fatal or put you within an inch from death!