Overall I love the premise. Parasites and the like are my jam.
That said, the game is pretty clunky. The reactor is definitely the biggest pain point right now. I don't believe it's mentioned, but having coolant higher than fuel means you dont get power in the first phase.
Switching between fuel and cycle in phase two is also a pain. I think with some adjustments to simply make it easier overall would be good. It could be an alright mini-game, but it's unclear and annoying right now, especially if you have to do it multiple times.
The left/right hand is clunky as well. Though it's not /too/ bad once you get used to it. It also has the unfortunate side-effect on requiring two hands to play the game.
Other than that, I'd like to see more clarity with enemies infesting you, and probably less enemies overall.
For example. a worm jumps on you, latches on to the body part, a second later, is half-inside, then fully inside. Giving players time to pull it out or what not.
Definitely want to see internal-view as well. as that's half the fun.
Also I feel like currently, the time spent inside the player is too short. It's basically popcorn.
Ideally, I think you'd want a slower approach, a handful of parasites slowly building up inside the player and increasing body-part proportions.
The reactor is currently a weak part, yes- the tutorial used to mention that about the coolant, but I scrubbed it when making it much less verbose. (Removed it in current progress.) The reactor is definitely going to be tweaked.
For the left/right hand, I'd like to eventually enable mouse-only controls, but that's lower priority over content and fixes. It does take some getting used to- I might add left/right indicators, later on, to help track what's where.
I am planning to make the entry/exit much more detailed, with middling frames before it's inside- this just requires a lot more art to accomplish. Internal view is a good idea, but hard to implement- I'll think about that one. A lot of enemies is partly the focus, at least for now- but I'm planning to diversify once I have more groundwork laid out, so there's room for different tastes.
As for the worms acting like 'popcorn', are you holding them in? They can be kept around by blocking their exit- best done by only enabling Chest + Crotch, and clicking said bodyparts. (Which, of course, should probably be explained before the dreaded reactor, instead of after.) Other than that, the current implementation is easy to change- it'll probably be tweaked as time goes on.