u/SpecialDisastrous985

​Hey r/gamedesign,

​I’m currently drafting the GDD for a 2D/2.5D psychological horror platformer, and I’d love to get some eyes on the core loop and mechanics before I lock them in. I'm trying to blend institutional horror with precision platforming, and I want to make sure the systems aren't fighting each other.

​TL;DR: Dual-campaign 2D horror platformer where you play two parallel protagonists. You navigate a "live" facility while using portals to enter hand-crafted, high-difficulty "Dream Mirrors" to grab keys/items. You have a strict 3-item limit, and digging too deep into the optional lore physically corrupts your world.

​Here is the breakdown of the core systems:

​1. The Core Hook: Parallel Protagonists

​You play through the game twice, as two different kids (a Boy and a Girl) existing in a multiverse. The physical map and the end goal (The Exit) are exactly the same, but their mechanics, backstories, and the way the world reacts to them are completely different.

​The Boy: Built for speed and panic. When he enters a Dream Realm, he has exactly 30 seconds to do the platforming before an invincible, god-like Guardian actively starts hunting him.

​The Girl: Built for technical precision. She doesn't have the Guardian chasing her, but her Dream Realms are massively scaled up in difficulty (pixel-perfect jumps, complex environmental hazards).

​2. The Setting: "Live" Institutional Horror

​Instead of an abandoned, ruined laboratory, the facility is fully active. There are "normal" kids taking classes, teachers indoctrinating them, and scientists taking notes.

​The horror comes from the contrast. You have to use "Social Stealth" to blend in with the normal kids. If a teacher catches you using your Dream abilities, they don't attack you—they call the "Men in Black" (the facility's enforcers), which triggers high-stakes escape sequences.

​3. The Main Mechanic: Dream Mirrors & The 3-Item Limit

​To progress through the 9 main linear zones, you have to use portals to enter "Dream Mirrors" of the rooms you are currently in. This is where the heavy platforming happens.

​Hand-crafted, not procedural: Every Dream Realm is a static, meticulously designed platforming challenge.

​The Vanishing Rule: You can only carry a maximum of 3 items back from the Dream Realm to the real world. If you drop an item in the real world to pick something else up, it instantly vanishes and returns to the Dream. You have to go back in and do the platforming challenge again to get it.

​4. The "Deep Dig" System (Lore vs. Plot)

​The plot is completely linear (Zone 1 to Zone 9), but the Lore is optional. The lore is found in hidden files scattered in hard-to-reach places. The twist: The Boy finds the Girl's files, and the Girl finds the Boy's.

​If you just play the linear plot, the game stays looking like a sterile, normal facility. But if you choose to "dig" and collect the lore, a hidden trauma meter fills up and the 2.5D environment starts physically manifesting their psychology:

​The Boy's World: Becomes paranoid. Overlapping whispers in the audio, and giant eyes start opening in the background walls to watch him.

​The Girl's World: Becomes visceral/predatory. The environment starts bleeding, and her actual player sprite slowly loses its human shape, becoming faster and more fluid/feral.

​Questions for the community:

​The 3-Item Limit: Does this sound like an interesting puzzle constraint for a Metroidvania, or does the "vanishing" mechanic sound too punishing/tedious if you make a mistake?

​Difficulty Balancing: How would you approach balancing the difficulty between the Boy's "Speed/Timer" design and the Girl's "Technical/Precision" design without making one feel vastly superior to the other?

​Live vs. Abandoned: Does the idea of a "Live" facility with NPCs running their daily routines make the horror more effective, or does it risk killing the isolated atmosphere usually needed for this genre?

​Any feedback, critiques, or pointing out obvious flaws in my logic would be massively appreciated!