I can't really think of that many, if you were ok with futanari protagonists you'd have a lot more options. Here's what I remember;
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aka 'Libra & Shota's Erotic Trap Dungeon': Shota/trap protagonist explores island which includes erotic traps, rapist monsters and monster girls. Also has feminization/sissification mechanic where protagonist can switch between masculine/feminine depending on what happens to them. It's translated too, though not available on this site.
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: Customizable protagonist in dungeon with traps, monsters and monster girls. Transformation focused like turning into a cowgirl or being feminized.
Max the Elf: Simple flash game inspired 2D sidescroller with trap protagonist that gets raped by monsters.
Lust Doll Plus: has customizable protagonist and I'm fairly sure there was some erotic traps and tentacles.
Happy Heart Panic: 2D platformer furry game with two playable characters, one being twink and includes some erotic traps & monsters.
I think the games by
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generally fit, like Lief the Vampire (Haven't played them mind you)