Old School Runescape. Pretty much everyone is using the Runelite client instead of the official one

https://runelite.net/

https://github.com/runelite/runelite

Exactly what I was after, thank you. Your other comment[0] with a link to game engine recreations is also super useful.

[0] https://news.ycombinator.com/item?id=36374297

Similar to this is there any example of someone building an entirely "new game" by changing the front-end client and assets so heavily that it literally becomes a different story/world/lure/characters? Essentially a total facade reskin?

League of Legends, Dota 2, and Heroes of Newerth were all directly inspired from a Warcraft III map mod, Defense of the Ancients. Multiplayer Online Battle Arenas, MOBAs, are now an entire genre.

I vaguely remember a mod called tower defense which we played on LAN, I wonder if that was the inspiration.

I've never played the map, but Aeon of Strife from Starcraft is a custom map that has the origin of Dota mechanics... and the Protoss Photon Cannon brought about some earlier versions of Tower Defense custom maps.

Of the 10 most popular multiplayer games in 2023[0] seven of them owe their core mechanics to mods / flashes of brilliance from a handful of amateurs.

A more or less correct history of their origins:

- Four of the games on that list are battle royale games, which started life as a somewhat popular Minecraft mod and really took off with "Battle Royale" - a mod of "Dayz" which itself is a mod of "ARMA II". It's mods all the way down.

- Two are tactical FPS games, which owe a huge chunk of their mechanics to "Team Fortress" a Quake mod and "Counter Strike" a Half-Life mod.

- One is a MOBA, which started life as "DotA", a Warcraft III mod.

Of the other three, one is Minecraft. Created by a solo dev, and I expect its moddable nature has helped its multiplayer popularity significantly.

One is Roblox. Created by two devs, and is itself a game creation system.

The final one is Genshin Impact - something of a an outlier in terms of team size and genre origins.

[0] https://twinfinite.net/features/most-played-games

Bungie's Myth II supported extensive modding (everything defined in the assets), so there's many total conversions that have been done.

Ace of Spades is one. I usually play with the OpenSpades client[1], but there is also Betterspades[2], and probably many other clients I don't know of yet. There are usually about 10-50 players online on the public servers listed on BuildAndShoot[3], variable depending on the time of day and mostly from Latin America it seems.

One can host the game with piqueserver[4]. I'm not sure if one can still host with the original Ace of Spades server, but the game was 'shut down' in 2019 so maybe not.

It's well worth a go - there is intense satisfaction in digging a tunnel undetected all the way through to the opposing team's base! Playing with friends enhances the enjoyment for me as one can be a little more strategic when in direct communication.

[1]: https://openspades.yvt.jp/

[2]: https://github.com/xtreme8000/BetterSpades

[3]: https://www.buildandshoot.com/servers/

[4]: https://www.piqueserver.org/

Second life is tangentially an example. they open sourced (or similar) the official viewer and some enhanced community and custom clients are out there like firestorm

oh, and quake 1's quakeworld client. many excellent quakeworld clients like darkplaces and ezquake. lots of one offs showing off tech, etc

There's several for Ultima Online - the original MMO:

- https://crossuo.com

- https://www.classicuo.eu

- https://libregamewiki.org/Iris2_3D_Client_-_for_Ultima_Onlin... - this is older, but really interesting as it's a totally different style to the official one

There are several dragonrealms clients, but most use Genie 3, and that's now been open-sourced.