Fountains of Youth in Video Games.
- In Blaz Blue Chrono Phantasma, about half the results of Amane Nishiki's Astral Heat turns his opponents into children. The other half of the results turn them merely younger (as in, from adult into adolescent or elderly werewolf Valkenhaynn turning into an adult). The only exception is Platinum, a youngish Magical Girl who instead turns into Trinity, her (sort-of) previous self. A few other characters Take a Third Option and become easter eggs, in-jokes or refferences to previous games.
- In Brain Lord, in the second magic shop you come across, you find it is run by three old women. If you go into the kitchen and talk to the old women there, she'll offer to let you try a new youth potion. Drink it, and instead of you being youthened, all three of the elderly women change to teenagers.
- The Case Of The Golden Idol: The eponymous golden idol has the power to make people younger — at the cost of taking years off other peoples' lives. Edmund Cloudsley utilizes this power to create a new identity for himself, faking his own death and becoming Lazarus Herst.
- In Chaos Rings III, Dorothy the kindly old caretaker and 'retired' adventurer who has been looking after the protagonist and his sister since their parents' deaths having the same name and voice actress as a much younger looking character is not a coincidence. Humorously enough, her youthful form looks younger than one of her sons, who looks older than his actual age.
- Coryoon have this happening in the backstory, where your owner, a princess, is hit by a curse that de-ages her to a child. You spend the whole game seeking for a way to break the curse.
- Civilization V features a Fountain of Youth as a Natural Wonder. All units that move adjacent to it gain the Double Healing promotion for free.
- In The Curse of Monkey Island, Guybrush is age-regressed to the form of a young child when he is trapped in the Carnival of the Damned by LeChuck. This also happens to him at the end of Monkey Island 2: LeChuck's Revenge, but is actually an illusion to trick him rather than physical.
- In Discworld II, the Fountain of Youth appears late into the game, as part of a puzzle where we have to find a way to prevent Death from dying. Subverted in that it's not the water we need, but the sand that lies at the bottom of the basin, so that we can refill Death's hourglass.
- In the PlayStation 2 and Nintendo GameCube versions of Donald Duck: Goin' Qu@ckers, Merlock becomes a child after he is defeated.
- Dragon Quest XI: Veronica is a Black Magician Girl in her late teens who gets turned back into a child as a side effect of the monster Jarvis draining her magic. This leads to some confusion when Eleven and Erik first meet her and decide to help her look for someone she describes as her "younger" sister Serena; they present a lost toddler to her who she never met before, but it turns out her actual sister is twice her height and (apparent) age. Even defeating Jarvis and getting her powers back doesn't restore her age, but, aside from her now baggier clothes and people treating her like a child, she's not too bummed about it so long as she can still help the Luminary.
- At the end of Emerald City Confidential, Petra deliberately does this to William to save him from life imprisonment and his memories of having been a Phanfasm spy.
- In remakes of Final Fantasy IV, a mist in Rydia's section of the Bonus Dungeon will turn her back into her younger version from earlier in the game, meaning she will not have her adult abilities available during this time, such as her summons.
- Kliff Undersn from Guilty Gear had the ability to use his ki to temporary regress to a younger form, when he was at the height of his strength. In-game, this only activates during his Overdrives.
- The Golden Suit in Henry Hatsworth in the Puzzling Adventure grants youth to whoever wears it. Henry's in his sixties/seventies, so when he dons it, he is restored to young adulthood. Cole, unfortunately, is only ten or so - so when he dons it in The Stinger, he's reduced to infancy.
- In Happy Hospital, you can build a literal Fountain of Youth where elderly patients can bathe in to turn into babies. You then take care of them in the nursery.
- In JoJo's Bizarre Adventure: Heritage for the Future, Alessi is able to use his Stand, Sethan, to revert certain characters to their youth. While this usually makes the characters weaker, it backfires on him when he uses it on Joseph. Due to Joseph already being very old, it only regresses him into his late teens. Unfortunately for Alessi, that was the age when Joseph was at his prime and beat the Pillar Men, who were FAR stronger than any of the Stand users in Stardust Crusaders. In Young Joseph's story mode, he maintains his youth for a while after beating Alessi, but it eventually wears off and he returns to normal, with him wishing it could've been permanent. Notably, Alessi can use Sethan on Young Joseph; this turns him into a slightly younger variant (the version of Joseph seen in a flashback of hijackers attacking the Joestar family's plane).
- In the King's Quest series, there have been 2 cases of this trope.
- In King's Quest II +: Romancing the Stones you will stumble upon a youth potion. If you drink it, you will turn into a baby and it will be game over. At the end, if you give it to the villain she will become a young woman again (good or bad depends on what you do). Trying to use it on Possum or Valanice yields unique sentences, but no penalty.
- In King's Quest VII: The Princeless Bride, the female villain is turned into a baby.
- The Legend of Zelda:
- Kafei from The Legend of Zelda: Majora's Mask was turned into a young boy by the Skull Kid not long before he was set to marry Anju. He was going to seek advice from the local Great Fairy about how to reverse this change when Sakon, a thief known to prey mainly on children and old folks, snatched from him the Sun's Mask that he planned to use in the wedding ceremony. He spends several months hiding from his loved ones in the backroom of the Curiosity Shop, not because of any current shame over his physical condition, but because he felt he needed to find the Sun's Mask first.
- Purah from The Legend of Zelda: Breath of the Wild. An elderly Sheikah who is the sister of Zelda's maid Impa, she had developed a magical rejuvenation process with the intent of increasing the number of young, able-bodied soldiers who could fight against the forces of Calamity Ganon. She decided to test it out on herself first, only to find herself physically a six-year-old. She has largely isolated herself with her assistant Symin in the Hateno Ancient Tech Lab, too embarrassed by her condition to face Impa or fellow Sheikah scientist Robbie. By the time of The Legend of Zelda: Tears of the Kingdom, she has partially reversed the process so that she now has the body of a young adult — still considerably younger than her actual age.
- LEGO Marvel Super Heroes 2 ends with Ravonna taking Kang's time crystal to prevent him from undoing his loss to the combined forces of the Avengers, the Inhumans, and the Guardians of the Galaxy and, after being unable to destroy him, uses it to turn him into a baby so he'll grow up to be less evil.
- In Magical Drop 3, the Final Boss Wheel of Fortune is sent back to the past and transformed into a baby after she is defeated.
- The "Babality" finishing moves in the Mortal Kombat games, in which the victor would somehow turn the loser into an infant.
- Seeing as how this is a franchise known for its violence, programmers wisely fixed it so the winning player lost control of their character the instant their opponent became a baby; the victor would immediately go into their win pose. The idea behind the babalities was to provide a more innocent alternative to the infamous fatalities. Unfortunately, a glitch was later discovered that, when exploited, allowed you to viciously attack the baby.
- Despite being unpopular with most fans of the series, the finishing move made a return in the 2011 reboot. This time instead of the opponent turning into a baby and sitting while crying, the babified opponent would now do a funny animation suiting their character. In fact, now, even the bosses can have a babality done on them.
- In My-HiME Fuuka Taisen, Yukariko's Child turns her opponents into young children.
- Mystery Case Files: The Malgrave Incident revolves around magical dust that has the power to rejuvenate people and that was the source of the curing properties of the once lively Malgrave Island's thermal waters. The elderly Winston Malgrave wants it to collect some his dying wife, although it turns out he wanted the dust for himself, so he could regain his youth.
- Nightmare Busters have this happening to Tyrant, the main villain, upon defeat, where he then turns into a baby version of himself. It's also a Karmic Transformation since Tyrant is a stealer of children's dreams who wants to inflict never-ending nightmares on children all over the world.
- Ninjala has the prototype ninja gum which turned the three scientists working on it back into kids.
- A fountain of youth is present on Easter Island in the Sam & Max: Freelance Police game Moai Better Blues, the reason that the island is populated by babies.
- In The 7th Guest, the elderly Julia Heine, after reminiscing about the beauty of her younger years at a Magic Mirror, is de-aged to a young woman eager to dance, then a pre-teen girl desperate for "Mommy", and finally a helpless infant. The Novelization retcons that this occurred after she was sent back in time upon sinking into Stauf's acid puke vortex at the end of the game, and that she continued to de-age into a fetus and was the one sacrificed at the altar.
- The Sims 2 had the Elixir of Life Aspiration reward, and the "milk" produced by the cowplant available in the University expansion after it eats a sim, which is a more potent version (making a sim 5 days younger per dose rather than three). The Generations expansion for the third game added the "Young Again" reward, which is Exactly What It Says on the Tin, and the Age Freeze reward, which is also Exactly What It Says on the Tin. And then there's the Fountain of Youth (literally a fountain) that came with the Hidden Springs neighborhood...
- Borf's weapon in the full-motion video game Space Ace turns people into infants. He had already used it on the main character, which turned him into a rather weak teenager, but at certain points in the game, the player can temporarily restore Space Ace to his proper age. And of course, he ends up being Hoist by His Own Petard.
- In Super Robot Wars Z3: Tengoku-hen, everybody is weirded out by the fact that Noriko's "big sis" who Noriko told them was a middle-aged woman, appears to almost the same age as Noriko. Kazumi giggles at this, and says that she somehow has the body of when she first piloted Gunbuster with Noriko. Kazumi thinks that after being pulled into the black hole, she wished and wished to see Noriko again. And that perhaps that wish overcame time itself, and thus she was reborn. Lelouch goggles at the mysteries of the universe and even C.C. comments that despite having lived a long time, she's still surprised by all this stuff that keeps happening lately. Noriko calls it a miracle born of Kazumi's feelings.
- In the Tekken Tag Tournament 2, Heihachi Mishima has found a way to rejuvenate himself back to his prime thanks to a serum made from Ogre's blood. This was brought about by Daisuke Gōri's unfortunate suicide, likely to justify a voice actor change, but didn't stick to the main plot as Tekken 7 shows Heihachi old again.
- In Tomodachi Life one of the random rewards you can get from granting Miis their requests is a Kid-O-Matic spray, which turns an adult Mii into a kid. There's also the Age-O-Matic spray, which does the opposite. Though if you use it on an old wrinkly, grey-haired Mii, they will still be grey and wrinkly, just shorter.
- Twisted Metal 2 plays this for laughs with Warthog's ending. Upon winning the tournament, Warthog's 105-year-old driver asks Calypso to give him the body of a twenty-year-old. So, Calypso gives him the body of a twenty-year-old. His head, on the other hand...
