In this game, you are the dude, and you are trying to find your way through a castle. Shoot your enemies or throw them into the goo and collect yellow shields for points, as you get an extra life every 2000 points. In the bottles with red fluid is a health potion, but you can only collect them when your health is down. Good luck!
Use WAD or the arrow keys to move and the mouse to aim and shoot. When you use the Gravity Gun, you have to click and drag. Press Q to switch between your weapons and hit the space to pause the game.