At first, watching this video, I thought I was experiencing some kind of meme singularity, a memetic big crunch that would hurl me back in time to some alternate 2003 where the current world had also still happened, a cosmic event of such proportions that I would never mentally recover.
Perhaps equally surprising, it was instead some madman who modded Halo maps into Dark Souls: Prepare to Die Edition, then rejiggered them to make them into maps for Dark Souls' Battle of Stoicism mode, then delved into deep places of the gamescript that no one should go in order to make it all work for 18 players. That's right, you can now play Team Deathmatch and Capture the Lizard on Halo maps in Dark Souls. There are even powerups to collect, like invisibility and fire arrows.
Modder and "unfunny video" creator Inferno Plus, egged on by his Patreon, has created Dark Souls: Remastest (opens in new tab). It's a remarkable thing, given how difficult stably modding Dark Souls is in the first place. In addition to its multiplayer components, the mod also does some TLC on the campaign, reworking some of the worst weapons and spells and removing obnoxious co-op restrictions.
Make no mistake, this is the David of Dark Souls mods. The Sistine Chapel ceiling of action RPG tweaks. The Great Wave Off Kanagawa of the You Died multiplayer experience.