Thanks for the review, PHI. I watched around 10 minutes while working on v0.0.0.1 and implemented some things you mentioned. Detailed change notes can be found at https://itch.io/t/253569/changelog.
Most notably:
-Completing a level goes back to Edit Mode without un-loading the level
-Ctrl-C and Ctrl-V now Saves/Loads as one would expect
-No more ghost icons when clicking buttons while playing a level
-Changed "Play" to "Play<>Edit" to make it clear that it's a toggle
After I get some food in me I'll keep watching your review of Slime Research and see if there's anything else that needs to be considered.