Having regrow would be a pretty neat feature to add to my bloons game, but the reason I did not add it is because of a new feature I made , so when you are at low health (for example 6/19) and upgrade ur health once, it upgrades back to ur original health (19) and of course adds one (+1)
oh yeah, THAT bug, I actually discovered this one a few weeks ago, so ig until I fix it this will be the closest thing to free-play mode. (ps. I'm happy that you are playing my game😁)