For those unaware, Ultrakill is an incredibly fast-paced and incredibly violent retro shooter where you regain health by dousing yourself in the enemies' blood. It's much more brutal than Doom and the most challenging part is to always keep moving, since the enemies are shockingly fast and you'll be ripped to shreds or killed in another ruthless way if you slow down even for a bit. This kind of intense gameplay allows for a feeling of satisfaction when you get into the flow, ripping apart monsters with various destructive weapons and healing with their blood.
The latest Ultrakill update introduces Firestarter, the red Rocket Launcher variation, and one of the final 3 missing weapon variations. Its secondary fire shoots gasoline, which can be ignited by any explosive. The Rocket Launcher has the fastest swap speed of any weapon. The Firestarter version's primary fire will either launch the rockets or create a large shockwave if none of the enemies are hit. Holding alternate fire will create a stream of gasoline, which slowly coat enemies and the floor in a dark, sleek cover. When hit with an explosion, it will set everything on fire and take more damage, the same goes for the player as well.
Recently, Ultrakill's programmer known as PITR has shared an overview of the mechanics and logic behind the Firestarter weapon, that would be interesting for both players and developers:
