Thank you for playing and the feedback :D!
At the moment sadly the game does not have a final end flag/state, we do have one in mind that we are going to implement after the jam/voting is done. Also with some UI additions so you know how many upgrades are left and stuff like that.
With the inaccessible areas, there were some planned upgrades/bosses we had to leave out at the moment, so they can't be reached yet (i think)! but hopefully soon :D