Delerium is a fun tank game where you'll be rooted to the ground in the middle of the screen and have to stand your ground. You'll use your mouse to move your cannon around and aim and then click it to shoot. You'll get a handful of different weapon types as you move along. Just shoot the weapon and you'll have a limited amount of shots in your arsenal. You will toggle through the weapons with your number keys one through four. You'll get more powerful guns and a laser. Each wave that goes by tallies your points and gets you ready for a more challenging wave on the next round.