"If you see a pink star, then RUN! With its all-destroying explosion, the iMPERiUS is the most powerful weapon ever. But this gun has two big disadvantages. The maximum ammo limit is set at two shots, and you have to hold down the fire key for a few seconds until the weapon is ready to shoot. But do not hold it down too long or the weapon will explode in your hands. Oh, and it shakes while loading, so it's not very easy to aim." — World of Padman Manual

The Imperius, also known as iMPERIUS, is a World of Padman counterpart of the BFG9000 in the Doom series. It functions similarly to the BFG9000 in Doom 3, washing out enemies within a large radius upon impact. The player's screen will shake while charging the weapon. Whenever the player charges the weapon for too long, it will explode and blow him/herself up.

•The Imperius is based off of the BFG9000 from Doom.

•The Imperius received a huge nerf in the 1.6 update of the game. Before, it was able to hold up to 5 shots, now it can only hold 2. Furthermore, the overcharge time has been reduced from 4 ticks to 3 before blowing up.

•The Imperius is usually very well hidden in both official and custom maps, so while trying to find or reach it, you will be missing out on a lot of frags. In some maps, the gun doesn't even exist altogether.

•Furthermore, this is the only weapon that is disabled in the Last Pad Standing and Big Balloon gametypes due to balancing. It is also not featured in any official CTL (and CTF in 1.2) maps.