You've a solid base for an FPS here. I couldn't find any bugs. I'd suggest being able to get the left UI off the screen. After a while it just seemed to invade my gaming experience.

Super cool idea! I really love the concept. The SFX bug where sometimes deaths of enemies are super loud is pretty annoying, but you already know about that as it was in the description lol.

I don't think the UI needs to be up with the controls at all times, the controls are very simple so I think it popping up for a couple seconds at the beginning then disappearing would be fine. It takes up a lot of the screen and is very distracting. Or maybe you could just have like "hold tab to show controls" be really small in the corner then holding tab pulls it up. Idk. Something like that though.

I didn't understand what to do in horror or in platformer. Was I supposed to jump on the enemies in platformer? I tried to a couple times but couldn't tell if I was being hurt or hurting them or if nothing was happening. I was just confused. Horror seemed like you just kinda stood there for a second and slowly walked away from them cuz they were super slow and easy to avoid. Also, horror mixed in with this isn't scary at all (if it's intended to be) because you can't really switch from a shooter to stealth to something genuinely creepy that quickly. Not saying you can't include horror, but just know that it won't actually be scary. But again, that's completely fine if that's not the intention.

During stealth you got another gun but it wouldn't shoot and I didn't know if it was something else entirely or what. Also, it seemed like I should've gotten caught a bunch of times but usually it didn't trigger, so Idk if it was a bug or if I was just barely avoiding them or what.

I also agree with everyone else that the map is wayyy too small, and it seems the only objective is to shoot the ghosts during the shooter phase. The map could shift around for different modes too sometimes, like maybe platformer some holes appear in the ground (just make sure they're not directly under the player haha) and you have to make it to a certain point of the map before the time runs out or you lose a life. Adding goals could be super cool. You could honestly do the same for stealth and maybe horror could be getting collectibles (like SlyBalto suggested) and you have to complete the objectives before it switches to the next phase or else you lose a life or something like that. Idk, stealth may not need it since avoiding being seen is a decent objective in and of itself, but horror and platforming definitely need some sort of objective.

Super cool concept though, very rough around the edges but definitely something that I could see being developed into something super fun.

This is a pretty interesting concept! Maybe for the horror one you could add the objective to collect items that spawn so it's not just avoiding the ghosts? I agree with LDPFDEV with their points including that the map is pretty tiny, maybe you could try a map with some more verticality + maybe it changes every few rounds? I.E. Some pillars randomly emerge from the ground to create obstacles or move themselves into the ground to make more space for walking around, which creates variation. Also, increasing the walk speed a bit could help too!

I think the HUD could be cleaned up a bit, there's a big dark transparent panel that could probably be removed since it feels like part of the player's vision is somewhat blocked. If the elements like the controls need to pop out more, maybe you could give them some kind of black outline or a drop shadow?

I really dig the idea that you gotta keep switching up your play style, even the weapon changes between Stealth and Shooter that's pretty dope! Hard to tell if it would be even better if there were more modes it switches between or if each mode had more depth, maybe more depth for each mode, I dunno.

Interesting game, colors and holographic style. Music is pretty good also.

Things to improve:

1. Sensitivity is very high (not a problem since my mouse has DPI change button)
2. Map too small