May be a bit too specific but maybe something with the tentacles sissifying/feminizing males, to make them either better hosts for tentacle parasites to feed on their lust or breeders for tentacles to reproduce, respectively; and/or conversely turning females into futanari, to make them produce more "nutrients" for the tentacles to sustain themselves, while still being valid hosts/breeders.
Or at the very least, maybe just for fun (or a "hard mode" type option?) have a way to put the "player" in chastity, making you have to work harder to start because the tentacles can't get to you as easily (though there are always "loopholes" to such a thing, and tentacles seem like they'd pretty easily find a "backdoor" to your defenses lol >;3). Should only impact the art for the player-focused section(s), so hopefully wouldn't add too much work.
Honestly I find it hard to think of anything not already in the game that doesn't involve femboys/sissies, futas, and chastity lmao. Maybe something with encasement somehow? Tentacles cocooning people in a sort of latex secretion so they always have a source of nutrients/lust/reproduction nearby? Maybe something with tentacle parasites merging so closely with their hosts that they become more like hybrids; think a humanoid Mimic from D&D, except they wanna lewd everyone instead of eat them lmao. Idk, just spitballing. I'm happy enough just to see what you're gonna be working on next ^-^