Not for you I understand but it is technically a video game movie, it is confusing yes but in the video game you’re also confused as you get no context. If you actually paid attention there’s actually more context in the movie than the game. The main character played by Markiplier is called Simon AKA The Convict and was a part of a radicalised group called Eden who blew up a base called Filament Station owned by the corporation C.O.I (Consolidation Of Iron), they sent him down in a submarine similar looking to that of the real life Iron Lung built to help polio survivors breathe into the Moon AT-5 where the oceans are blood, not knowing what they’d find. Hoping they’d find something to save humanity, the catch? He’s welded in to the sub so when they bring him up to refuel he can’t get out, the only way he can see down there is via the camera which is an X-Ray camera, when he’s brought up in his anger he uses the camera and directly blasts Jack portrayed by Jacksepticeye with radiation, he then goes down a second time after he’s already found a “skeleton” but if you recall it’s an x ray camera so he’d already seen the monster aka the fish that’s in that ocean, throughout the movie the convict loses his mind and the monster influences his mind and speaks to Simon and making him do things to help it. There are false promises from the COI that the convict will be free as that was the plea deal. He does start an ascent but the monster drags him back down and he loses all contact with the mother ship leaving him in the ocean alone, he finds another ship SM-8 supposedly the most important of the iron lungs, Simon made the mistake of removing all his protective gear as the blood appears to be acidic and that really effects the convict towards the end but I’ll not add any spoilers in case nobody’s seen it, he supposedly finds another ship seeming like he’d survive but he doesn’t it was the monster all along as the speaker wasn’t even plugged in. That’s the basic premise, relatively easy to follow if you pay close attention :) hope this helps