id Software’s Doom reboot launched on Friday the 13th (how fitting) following months of teasers and betas. While its multiplayer modes are likely getting the most attention, plenty of gamers are having a great time working through Doom’s single-player campaign.

Those looking for a serious challenge are invited to try the campaign on Ultra-Nightmare mode which cranks the difficulty to 11. Aside from everything being much harder, Ultra-Nightmare mode features permadeath which means if you die – even once – it is game over and you have to start over from the very beginning.

A few weeks before the game came out, Executive Producer Marty Stratton and Creative Director Hugo Martin told IGN that nobody at id Software had yet managed to beat Doom on the hardest difficulty setting.

Remarkably, it took a gamer by the name of Zero Master less than a week to complete it on Ultra-Nightmare mode. Video of the playthrough was uploaded to YouTube on May 15 meaning it took just two days to pull off the feat. That’s hella impressive (no pun intended).

The entire process took four hours and 47 minutes, all of which is shown in the video above. Zero Master said he ran the game on low settings with minimal field-of-view which is a common tactic as things like high-quality smoke and enhanced debris can severely limit your view and thus, get you killed easier.