In ULTRAKILL you play as V1, a machine designed during war for absolute bloodshed, featuring extreme agility, power, and the unique ability to regenerate itself on contact with fresh blood. The first, and only, one of its kind, entering hell in the hopes it will provide sustinence
In this game, you have multiple options at your disposal to decimate your prey
dashing
Starting with base movement, you can dash, slam, slide, or wall jump, each of these on their own are self explanatory, but you can mix and match these in order to get really far really fast. Possibly the most fun out of these though is what is called "slam storage" where you start a slam against a wall and wall jump a few times while you keep slamming in order to gain incredible amounts of momentum, which you can use to fling yourself essentially. You can jump right after landing the slam to get incredible height or you can initiate a slide jump in order to get a lot of horizontal distance. Slam storage is one of the most valuable pieces of movement tech as you can use it to get away from enemies really quickly or to quickly progress through a level
using coins
railcoining
The weapons featured in this game are incredibly intertwined with one another, each serving a unique role in the weapon sandbox. First, and most versatile, you have the revolver which does its regular shooting, and when you get to a variant of the weapon, it gives you the ability to throw coins which can deflect attacks from other weapons to enemies or from enemies to enemies. The simplest thing you can do with the coins is simply use it to get more damage out of it, as it redirects your shots onto the most vulnerable parts of an enemy. You can combine these coins with other weapons, which allows you to do things like railcoining which does double the damage of the railcannon with one shot.
V2 preparing to fight you a second time
All the levels in this game are incredibly fun, and challenging. The first really challenging level you encounter is when you encounter your doppelganger for the first time, V2. V2 was created during time of "peacekeeping" and since bloodshed was no longer necessary, V2 lacks the signature ability to regenerate upon contact with blood, which means better plating so it's more durable than you. The other main difference other than the regeneration is that this machine features an explosive punch for its melee rather than the ability to parry like you do. With these differences aside you duke it out, and like an idiot it doesn't use it's exploding arm during this fight, granting you a kinda easy win against your doppelganger. You meet V2 again later on, it's seething about your past battle, and it has learned some of your techniques, notably using coins. This time it's much much more challenging to fight it. Again like an idiot it doesn't use it's own unique arm against you, which effectively gives you a grapple arm. Oh also V2 is very dead after this.
gabriel jamming
After clearing the layers of hell, one by one, the judge of hell Gabriel tries to stop you. Upon the first time you fight him it's inside the huge corpse of king Minos, and there Gabriel calls you an "insignificant fuck" after you beat him ;-; Anyways you fight him later again and this time you beat him up again after you interrupt him playing the organ. But instead of insulting you, he realizes that there's no point to the heirarchy of beings, and so he kills all the tyrants plaguing heaven, knowing he will die in a day anyway. So that's that with Gabriel.
minos prime breaking down
Upon the completion of Act I, you obtain the ability to fight the former hardest boss in the game, Minos Prime. To fight him you must've P ranked (so perfect everything) all the levels in Act I. Once you're in the level you must beat the devastating Flesh Prison, created by the council of heaven in the fears of Minos' soul's power overcoming their own. This is honestly the harder part of the level, as you need to be in constant movement to dodge its attacks and also make sure you kill the prison's healers that spawn incredibly frequently. Upon the killing of the prison you unleash Minos Prime, his soul develops and he materializes into a person shape, giving you a speech about how Gabriel will pay for killing him and about how you suck because you're a machine, so he tries to kill you. It's a pretty hard boss fight but honestly easier than the Flesh Prison you fight a second earlier.
sisyphus also breaking down
Stepping up drastically in difficulty, you get to the hardest level of the whole game at the time of writing, Sisyphus Prime. Unlocked in a smiliar way to the Minos Prime fight, you must P rank all of Act II, then you unlock P-2. After starting an insurrection during the power gap after God leaves heaven, Gabriel kills him, rendering the hopes and dreams of all the insurrectionists abandoned. Sisyphus' soul is not like Minos, souls need mortal status and willpower in order to manifest into a physical form. Sisyphus' status was nothing like Minos' kingly status, his kingly status and his immense willpower was enough for Minos to become a prime soul the council of heaven feared. Sisyphus was incredibly powerful, more so than Minos, to the level that the council had to create an entire gauntlet and panopticon in order to contain the power of his soul. Imagine for a second, since he was more powerful than Minos and had no high mortal status, he was running off pure willpower. He does not have a noble goal to attend to, he doesn't wish to seek revenge or bring justice to the corruption brought upon the council of heaven, he just wants to cause chaos. Anyways you complete this ridiculously hard gauntlet that takes soo so many tries even if you've put 100 hours into the game, to then fight the flesh panopticon, which contains Sisyphus' soul, upon damaging it a little his partly formed soul is strong enough to destroy the rest of the flesh panopticon. He gives a speech about how he's gonna destroy heaven and before that you're his appetizer so boom you fight him and kill him after a million tries. This boss fight is quite harder than fighting Minos Prime, especially if one doesn't look up things about the game. And once you kill him he doesn't give a heartbreaking speech about how he couldn't complete his goals, he just laughs it off because he finds everything amusing, honestly badass way to go. So overall this level on the hardness scale is 10/10 in every part at the time of writing.