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Level Menu

A menu that lets you directly go to any sandbox level, hub or mission that is currently available in the game.

Enable the mod.
Ingame press ESCAPE to pause menu.
You will see a button that says "Level Menu".
You can also access the menu from the mod options.

I will later add a third list with all the modded maps you have installed so you can start those aswell from this menu, for now it is not possible through script, hopefully soon.