ONI's bugs killed me. You spend a zillion hours building up a colony, then another few hours routing up some wires to get a closed feedback system, and then the system glitches and cant resolve the wire routing or the pipe routing or something and it all breaks down. Frustrating like a programming language with no error messages and a buggy compiler.
When did you last play? They frequently release updates/bugfixes so you might want to pop in again to see if things haven't improved.
Also that's where creative mode really shines - to test out ideas because getting the proper ratios plus fighting bugs can take a lot of trial and error i.e. "debugging".
Do you mean fighting bugs in the code, or literally fighting those weird bugs that fly around the caverns? Do they get aggressive, like the biters in Factorio?
You don't have to fight any critters in ONI, at least not that I'm aware of. You can kill, cook, wrangle, breed and farm them for resources, as many of them provide useful input/outputs, such as feeding Hatches your "trash" in order to produce coal. I often to refer to this list for help with which ones are useful: https://oxygennotincluded.gamepedia.com/Critter
