So, "You can't let him in here." I am so not happy to see this one come up, but I'll work with it.

So top level ideas: you're limiting a specific person or thing or class of things from entry. Either something about the player or a companion doesn't allow you into a place, or you're tasked with keeping others out.

I've got a couple of first pass ideas on how to take this:

I could make a political statement: I could figure out mechanics that help model the emotional resonance of being a trans woman in a world where "bathroom bills" are becoming daily news. This would be a game more about identity than game place, and I'd be limited to a short prototype rather than a functioning game. Set up mechanics that let the player choose the identity they'll be playing, then slowly clamp down on their expectations.

The second idea is kind of like the other, except someone you keep with you limits what areas you're allowed in. This could be a tiny action game? Maybe use a symbiosis mechanic.

Last idea is building a reverse stealth game with something similar to tower defense mechanics. A lot harder in 2D, but possible. Makes vision management fun, though.

I'll start drawing things up and make a decision by the end of the night.

Mostly because I believe in documenting my process, I took the three tiny ideas and attempted to flesh them out.

The political statement game came off because I couldn't build a decent proposal document.

So the other two:

Security Maze

Play the other side of a stealth game: You're the bumbling guard. Early on, it's just you and your wits against a hidden enemy. But then you start getting tools that will improve your ability to track and catch your prey. Or simply keep him out until he runs out of time.

Primary Game Mechanics:

• Limited vision. Only see where you have eyes, right in front of you, or in range of any cameras you place.
• Limited mobility. Your prey is faster than you, which means it's only your planning that will keep them out.
• Security gear. Noise traps, cameras, barriers and more to track the intruder, slow it down, and help you stop them.

Symbiotes

Beat monstrous warriors and creatures, collect their battle spirits and combine their best qualities into yourself. Become the perfect warrior: the symbiote.

An idea that borrows from Shadows of the Colossus, Titan Souls, and Megaman and combines them.

• Symbiotes and equipment: Equip your warrior with symbiotic spirits and conventional equipment to take down bigger and badder beasts.
• The Beasts: Each encounter is a specially designed beast with unique attack patterns and skills. You'll need to master the combination of skills the symbiotes provide.
• Shops: The symbiote is a terrifying creature, and depending on the spirits you're most attuned to, certain citizens will keep you from their businesses. Good luck getting rest when the inn stops letting you in.

Experience

I want to counterpoint RPG style minmaxing and power fantasy with a feeling of being shunned for becoming more and more of an outlier. To that end, various shopkeepers and NPCs will begin to avoid you as you collect spirits, leaving you with the hard decision of giving up skills to continue receiving services.

Mechanics

There are three primary mechanic concerns:

Combat

Combat will be a shoot-em-up style top down game. Each encounter will be an arena style combat with one or more enemies, one of which is the goal. Defeating this creature spawns the spirit that you add to your collection.

Enemies can have several states, special weaknesses, or weak points. Their attacks can vary greatly from battle to battle.

Equipment

There will be "basic" equipment that lets you tune your stats to match various enemies, but the amount of customization is limited.

Once you get spirits, they become available as special equipment that have higher stat changes and provide special behaviors.

Aid

To change some of the assumptions RPG style games have, remove currency as a resource, and leave the standing with NPCs the only access to various aid.

This includes the armorers, the inn, alchemists, mages, doctors and other out of combat aid.