Yeah, we tried to design the first four levels with the intention of introducing the game's mechanics to the player, as a sort of built-in tutorial. I'm relieved to see it working out.
As for the number of mechanics, we actually had a bunch more ideas for other mechanics, but decided to scrap those to focus purely on a few instead. I think that's probably our best decision yet, otherwise the game probably would've been a mess.
Thanks for playing!