Sorry, more thoughts on this.
The general idea of First Person would be so you can see your bloating progress. As you get bigger, just seeing your gut distend in front of you. Bigger and bigger. It starts making you slower and slower until you are basically just waddling, watching your body jiggle with each step.
The monster would be a balance of trying to save yourself and the crew. The more you disturb it, the more it will go after you. But at first, it doesn't even know you are there. So if you stealth very well, you can beat the game without taking damage. However, the monster would be eating the crew as you go.
You could just bee-line it to weapons and 1v1 the monster, but it would be far more likely to attack you and any shots you miss would have a decent chance to pop a crew member.
I also envision the old pilot swollen stuck in the door to the bridge; the location where the final choice and cutscene(s) would get triggered. You *could* just grab a weapon and pop the pilot, or lure the creature over and convince it to eat the pilot, ending the game quickly, but you would get a bad ending/bad score.
Along the way, you'd also get basically med kits. Researchers on the ship before you arrived found the main chemical that can counteract the monster's venom, so you aren't starting from scratch to find the full cure/vaccine. Plus, you can inject yourself or other crew members to slightly slow down the swelling to either allow yourself to take another hit or squeeze by someone to get into a room earlier than "intended." But, you do still need them to research the cure, so each one you use would slow down your progress.
I'm envisioning a few endings.
1. Where you see the monster and say Fuck this shit I'm out. Get back on your ship and leave.
Then 4 endings based on how many crew you save and whether or not the creature is still alive.
You would make it to the bridge and decide to either take what survivors you can (can't fit everyone this way) into your ship, blowing up the downed vessel as you leave. Ensuring the Monster goes down with it.
Or you either subdue the creature or kill it, make the cure, and fly the ship itself to safety. Bad, Neutral, and Good Endings based on how many survivors.
(Secret ending where you have everyone escape alive, but it's near impossible to achieve. I would personally kind of do a FNAF UCN where I don't even check to see *if* it's possible before game releases. And just allow the players to view the ending as a reward for, like, a harder achievement. Like saving X00 crew members across all playthroughs. But also have another reward granted as well. Both as a reward, and in case the scene is actually viewable. Wouldn't make sense to earn the scene twice. A reward like a bloat gun. Something to use on the monster to make it swell up and make the game trivial. Then use it on the crew members to make their bloating less body horror, and just swell them round, so you can just roll them around. No hunting for the cure or using resources to get where you need. Just turn them into a ball and roll them out of your way.)
Anyway, ADHD'd a little hard on this. I think it would be a fun game to experience the horror the first time, then try to speedrun on repeat attempts. Almost like either a roguelike with randomized rooms or just keep everything the same and add a game timer to see how quickly you can escape