Maybe some kind of jedi like character who looses the force while clothed, or area status effects based on lack of clothing. Maybe a skill that once learned makes you more powerful, but requires you to be nude. It be a challenge to incorporate the nudism without it being gimmicky. It would be sweet though, I'd buy it for sure.
I've thought that something like swimming in a game would be better accomplished if your character stripped down and left items behind, or for every piece of clothing and gear the character's ability to move through the water slows down.
Wouldn't it be more about the depiction of the main protagonist - a strong appealing person, a role-model, who doesn't give the time of day to think of such a trivial thing as clothing. Then it would be a matter of climate, environment, that can physically justify the nude form. Beyond that giving clothing or the lack of clothing a minor to no role.
Then creating an in-game culture that lacks any inter-personal ques that define nudity to be against the public norm. Have a nude person and a clothed person having a normal talk without the 'you are naked, why are you naked, you should put some clothes on'- dialog. One in-game culture could be a prehistoric tribal one, where you can create characters with more colourful appearance in the way of hairstyles, body paints and adornments and work from there, creating factions and relationships between people and groups. Far Cry Primal had a good game-world that could have worked this way too.
One idea; if I would create a game where protagonist would have an interest, a need, to get naked. Player starting in a jail cell covered in a rigid suit (straight jacket) or something that would otherwise have inhibitory function (
@Longingtobenude thanks for the idea) and then you would need to start moving around in the prison complex and find ways to break pieces of the suit off his person, to be more agile, more unencumbered and work through environmental hazards like a sunken ruins of a medical ward (
@Maverick thanks for the idea) or swim away from a prison island. It could be a grim possible cyberpunk future. Or then the protagonist could be the sole prisoner in a rundown prison island and he needs to work out how he got there while getting clues that there is someone else in the prison noticing his absence and then starting a hunting game.
Just a quick idea.