Looking for a close to 1-for-1 2007remake source + client for personal use

This might sound "forever alone" but I basically am looking for a 2007scape/oldschool sort of server with no bells or whistles, just like a normal Runescape Private server for personal use.

I basically want to self host the client/source from my desktop and just play alone like a giant single player game with no other players.

If anyone can provide me a close to true-to-2007scape experience let me know. If it has nothing custom, nothing unique, that's sort of what I'm looking for, just a Skyrim like single player game that I can install and enjoy for years to come, preferably with 1x Xp rates, just like normal.

I'm sorry if this sounds really weird.
I'm willing to pay a bit for this if you can provide working proof of something like this. Of course if theres an open sourced project like this that would be preferable. I don't like the current state of the game and I'm hoping to "safe guard" a copy of the game essentially so that 30 or 40 years from now I can still enjoy the game I remember. Basically a time capsule. Thanks.

Regards,
Krythix