We have big updates to the save system in this build!
The new save system will save everything related to a particular world into a singular .universe file in the Worlds directory (currently about 120MB). It does atomic saves and maintains a list of 5 rolling backups, so it should be much easier to restore if something happens and should sync much more easily using Steam Cloud (also will help keep us from hitting the Steam Cloud 10K file limit with multiple worlds!)
Save migration will happen automatically - the build will load the directory-style saves from earlier and just save to the new format when the next automatic save happens. It will then prioritize the .universe file save over the directory (ignoring the directory if there is a same-name .universe file). New players will never have the directory-style saves.
ALSO: you can save your own backup or create a branch of an existing world by using "Save As..." button in the In-Game Menu. When you save the world under a new name, the filename you choose will be seen as the world name in the World Select Menu (and the existing one will still be there).
Hopefully this fixes all of the issues that previously existed with saves! I'm also going to make the savefile size more compressed (right now there's a bit of a hitch when you first select a world because it has to load the entire file from disk before deserializing it), but I wanted to save that for a later change so there isn't too much happening at once.
Let me know what you think of the new system! It should prevent data loss and also make it way easier to branch off backup copies of worlds or share them with others!
and if you haven't already please leave me a Steam review, it really helps me a lot!
-Triplejump