I have ideas for a game where there are three player sizes, tiny, mini, and normal.
While mini, the boss will attempt to eat you.
While eaten you are paralyzed but the boss is not. You take acid damage and strangulation damage. The boss will regen health as you lose it. Some big hits dealt to the boss will hit you as well.
If you shrink further inside the boss you can fuck them up from the inside but take much more acid damage.
But if you make yourself larger you take much more strangulation damage while still taking the acid damage but take out the boss with their cartoonishly large belly immobilizing them.
Rather than make vore a simple game over I wanted to give the player agency to decide whether to let their teammates save them or them to turn the tables on the predator in funny ways.