Fast paced action first person shooter. Earth has been invaded by demons many years ago. The demon rulers have slaved, tortured and killed everyone who resisted. You decide to fight back! The demons found out you were plotting a rebellion against them and the demons are now hunting you as an enemy of the state. Your goal is to start a rebellion and overthrow the evil demon rulers and their minions. Slaughter large masses of evil demons, zombies and other monsters in colorful environments. The game runs on FTEQW engine.
A trailer sort of short video from a level called Vengeful Entry which is possibly a first level in the game, or first level of one episode.
Spoiler Warning: If you absolutely want to see the full playthrough of the level, you can see it here, but it will spoil all the secrets etc: Youtube.com