Glad to hear you guys are working on mechanics! As for the difficulty, yes that is usually the hardest problem to solve in a bondage game (since snowballing into loss all the time isn't fun per se, but also if its too easy then the bondage doesn't feel legit). One idea that might help is to make things on the more challenging side, but also have some kind of mechanic or system where if the player loses, they get some kind of benefit to make it easier the next time. For example, perhaps on the second attempt, the enemy will spend a turn or two gloating (so the player effectively gets an extra turn or two). Just an anti-stonewall idea. Another version of this is in Magical Girl Luna, in which, after the player loses, Luna's mentor pops in and gives advice on how they can win ('The enemy does a strong restraining move after this thing, you can Defend to prevent it', etc.).