Dungeon Crawl Classics. Many of the adventures leave characters with permanent physical changes. For example, my now-8yo's halfling has undergone the following metamorphosis since the campaign began:Okay, I need more than 5 words on this one.
- Head changed to a grinning silver skull with red diamond eyes
- All hair gone from body
- Strength score boosted while Personality score dropped (DCC has Strength, Agility, Stamina, Intelligence, Personality, and Luck)
- Strength score boosted while Agility score dropped
- Intelligence score boosted and Personality dropped
- Found an intelligent magic sword that is smarter than the halfling.
- Eyes warped and bulging out of skull
- Strength score boosted and Luck dropped
- Mind warped with nightmares and visions of alien realms plus the ability to cast a couple of spells
All of the changes (except the Ioun stone) came from officially published - or at least officially sanctioned/approved - DCC adventures. The kid loves it; the goal for the character is now for him to become a "full-on demon." To keep from scaring townsfolk, the character wears a paper bag over his head with googly eyes on it (in a 7yo's mind, this appearance is apparently less terrifying than a silver skull with red diamond eyes, though I feel that's debatable).
Anyway, in the adventure we finished yesterday, one room had a curse with an absurdly difficult saving throw DC and all characters failed the save. The effect of the curse was that everyone passed their character sheet to the player sitting to the their right; characters retained their minds and personality but had the abilities and features of the character they were handed.
Hence, "New curse: characters switched now."
For the record: the kid did fine with playing the elf, but their spirit wasn't in it. They missed their super-strong "halfling." Luckily, the adventure had a "if everybody is tired of the character switch do this" epilogue, so I didn't even need to make up a denouement to fix the situation myself.
Dungeon Crawl Classics, folks. There's no other game like it, and it absolutely rules. Here's an illustration I drew of my kid's character in action (which I also made into a sticker, a copy of which is now stuck on their bedroom door).