In fanfiction recently I've seen a recurrent trope where an achievement in one "life" of some kind of survival RPG game unlocks the ability to use a functionally different avatar to start the next playthrough of the game. Other than Tokyo Jungle, what games have this mechanism? Just driving me crazy that this is apparently a widely known concept but I must have missed the source game, lol.

I am not sure if this is the source game, but Spider-Man 3 Video Game has the mechanism that unlocks the black suit after you beat the game.

The Binding of Isaac has this as well, although I'm sure it wouldn't be the first.

They aren't RPG games and didn't explicitly feature "achievements", but as far back as Mortal Combat arcade cabinets in the 90s you could unlock hidden characters or the ability to play as boss characters by achieving certain goals, which is pretty much exactly the same mechanic.

Also not an RPG, and I may be mistaken, but I feel like popular FPS title Golden Eye for Nintendo 64 may have also featured this.

It's also extremely common in car racing games where it tends to be one of the main forms of advancement.

Also not an RPG, and I may be mistaken, but I feel like popular FPS title Golden Eye for Nintendo 64 may have also featured this.

You are correct.

The Gauntlet Legends arcade game had bonus characters that you could access through completing parts of the game as well. It was a novel game in that it allowed you to save your character on the machine with a password so that you could come back later and play it.

Fascinating! I guess this is an example of how a good idea tends to stay within a genre or two for a while before making the jump to the wider world of game design; an idea has been around for years, but in genres I don't play, so I never encountered it, or encountered it only in the degenerate case where the only thing unlocked is an alternate skin (Okami has this IIRC) rather than real functional differences, like a set of game+ settings. I've observed this sort of cultural barrier before, between genres before when comparing virtual pet games/social gaming sites to console RPGs and MMORPGs. I definitely don't want to be trapped in that kind of narrow realm of thought, seems like a big handicap for any designer.

The unlocked avatars possess different skillset and sometimes the levels are designed that only these avatars can access certain areas. For example, you just unlocked a character that can jump twice as high. The first level has some areas that can only be accessed by this character, revealing hidden secrets and items.

In fanfiction recently I've seen a recurrent trope where an achievement in one "life" of some kind of survival RPG game unlocks the ability to use a functionally different avatar to start the next playthrough of the game. Other than Tokyo Jungle, what games have this mechanism? Just driving me crazy that this is apparently a widely known concept but I must have missed the source game, lol.

This has existed in MUDs for decades. Often called "remorting" (or "rerolling" or a few other things, all of which can also refer to different systems; sigh). After reaching max level (which is as close as you can get to "beating" an online persistent game) you are offered a reward for restarting by either having new races/classes/skills unlocked or by having your next character starting with higher stats (and having a higher ceiling at max level).

Star Wars Galaxies is an example of a more modern MMO doing something similar by requiring players to max out certain professions before being allowed to create a Jedi character. I personally like this kind of system as it exchanges the endless grind at max level utilizing a small amount of content with incentive to start over and re-experience lots of content in a new way.

Some games just do this via difficulty levels. In Alan Wake, for instance, you could unlock the Nightmore mode. This didn't make Alan more powerful but it did unlock a few small shreds of additional story. Games with unlockable difficulty modes or New Game+ modes are quite common, of course, and have been around for at least 25 years.

In fanfiction recently I've seen a recurrent trope where an achievement in one "life" of some kind of survival RPG game unlocks the ability to use a functionally different avatar to start the next playthrough of the game. Other than Tokyo Jungle, what games have this mechanism? Just driving me crazy that this is apparently a widely known concept but I must have missed the source game, lol.

This has existed in MUDs for decades. Often called "remorting" (or "rerolling" or a few other things, all of which can also refer to different systems; sigh). After reaching max level (which is as close as you can get to "beating" an online persistent game) you are offered a reward for restarting by either having new races/classes/skills unlocked or by having your next character starting with higher stats (and having a higher ceiling at max level).

Star Wars Galaxies is an example of a more modern MMO doing something similar by requiring players to max out certain professions before being allowed to create a Jedi character. I personally like this kind of system as it exchanges the endless grind at max level utilizing a small amount of content with incentive to start over and re-experience lots of content in a new way.

Some games just do this via difficulty levels. In Alan Wake, for instance, you could unlock the Nightmore mode. This didn't make Alan more powerful but it did unlock a few small shreds of additional story. Games with unlockable difficulty modes or New Game+ modes are quite common, of course, and have been around for at least 25 years.

I think the western RPG version is a little different - in all the examples I've seen the unlocked avatars are variants on a precreated character, with at least two of: different backstories, different abilities, or different appearances; but the plot that this character lives through is the same, so they can try to accomplish things they failed at last time. For this, the fact that the character remembers their previous life is important. Now, I can imagine that in a wRPG getting a character to max level or beating a final boss unlocks the ability to be reincarnated as a member of a different race (maybe a restricted one), and keep or regain one's memories of the previous life. It just doesn't seem like the usual way this works in wRPGs.

Also not an RPG, and I may be mistaken, but I feel like popular FPS title Golden Eye for Nintendo 64 may have also featured this.

You are correct.

He is? I used to own it, but been so long that I can't recall it ever doing that. I know that as you beat the game you unlocked multiplayer skins. Also remember doing the goofy cutscene glitch where Baron Samedi is walking toward you and you can shoot and kill him for good.