>>49626598>is it possibleYes, sure.
>while still using its normal RPG mechanics like catching and battling?You just need to decide on the horror tools to use that work with this.
If I were forced to make something, I'd go for discomfort and dread. I would make the spritework unsettling, and primarily in dark tones. I would make the story a Parasect-flavored apocalypse, where the mushrooms have become able to infect other species. I would make it so the Box system is down and you only have 2 or 3 Pokeballs plus your starter.
Whatever Pokemon you do have can become infected from battles with infected, and their spritework will change over time to show that. The only indicator for infection is the spritework, how long they take to respond to commands and if they follow them, and how they behave during downtime. Evolving an infected Pokemon causes the infection to jump several stages.
The downtime will be at camp sites where you sit with your Pokemon, who have to be out to guard you while you sleep. Depending on infection levels their behaviour will change during this, and at high infection you might need to play a minigame where they slowly lean in to attack, or creep down the cave from their post illuminated by flashes of lightning, or something.
There's no way to release Pokemon, your team will refuse to leave you at all stages of infection.
The big horror gimmick is that the innate trust in your team is what's being questioned, and though there's no human enemies, infected human corpses litter some areas.
If the player gets hit, either through blacking out or during camp, they don't get told of their infection. Instead there's a short level of bizarrely empty travel where the camping is skipped.
When they get to the end the survivors order their Pokemon to attack you instead, and you get the obvious reveal and the bad ending.
Getting to the end without getting hit as the player is the better ending, but it costs your team. There is no feel good ending.
