A_Lost_Dog there is a way actually that you can still do it if you don't mind getting into 'the nitty gritty' (it's not that hard really) Go into your 'worlds' folder in your minetest folder (on Linux it's /home/yourusername/.minetest/worlds) and you should see folders with all your saved worlds. Rename the world folder you want to and then enter the folder. Open the world.mt file and change the line that says world_name = youroldworldname. Change this to the new name (has to be same as folder name) and then you're good to go!
I would real like to be able to rename a saved game
You mean renaming worlds? That's an engine feature request: https://github.com/minetest/minetest/issues/10147.
A_Lost_Dog there is a way actually that you can still do it if you don't mind getting into 'the nitty gritty' (it's not that hard really) Go into your 'worlds' folder in your minetest folder (on Linux it's /home/yourusername/.minetest/worlds) and you should see folders with all your saved worlds. Rename the world folder you want to and then enter the folder. Open the world.mt file and change the line that says world_name = youroldworldname. Change this to the new name (has to be same as folder name) and then you're good to go!