I think you both have good ideas here. This is definitely a setting I’d like to see in a short narrative, CYOA-style, if it’s from the protagonist’s POV. Basically, you’ve gotten yourself lost in the factory. Maybe you’ve accidentally discovered the owner’s devious intentions, so now you’re trying to find a way out. But each room you encounter fattens or fills you somehow. Where most CYOAs give you items, this one give you traits, like how big you are in places, and then the game reacts or changes what choices you have access to based on what traits you have. For example, if you have the ‘Round’ trait, meaning you’re basically a shuffling ball, you might come to a ramp and can’t help rolling down it into more trouble. Otherwise, you’d be able to avoid it. If the layout of the factory, and therefore the paths you take, could be procedurally generated then the factory can change and affect you in different ways each time. Just some thoughts, cause I’ve been wanting to see a weight gain CYOA for some time.
Obviously, a management game would be more of a simulator like Fetish Master, and so would be more involved. The trick would be making sure it’s not too dry. I’ve played some life sim games, and FM for a bit, and it always feels like you’re doing a clicking routine 90% of the time hoping to stumble into something interesting. The first idea that comes to mind is that you start off small, with one or two basic ‘procedures’ like blueberrying someone. This leads to a minigame or series of choices where you change or fatten them up. Here’s the catch: the better you do at the minigame, the more successful and productive the procedure is, giving you revenue to expand your operation; the worse you do, the more interesting the results and the more progress you earn towards researching new procedures and facilities.
Example of a procedure: the Soda Room. You have to entice the subject into trying a soda that turns them into a balloon, without them hurting themselves or even popping. If you keep them at a managable size, you can turn them into a floating sign for the factory, adding ad revenue. If you fail (too big or not big enough), you don’t make money, but you learn how to better refine the recipe for the soda or unlock other procedures to try.