when I accidently clicked save to instead of load. So I overwrote my map with the custom plain green start map.

Anychance to recover it?

You can try restoring the file to a previous if you're running Windows, using the Shadow Copies if there are any.

Ye tried that but the last loadable copy version does not include it. Just started working on it this morning but still were like 3h of time invested.

Ok since it seems that my work is gone I atleast want to use this expirience to suggest a "lastplayedlevel.png" for everything you started with the editor play button last.