Спасибо большое, а то заплутал =)

There's an armor upgrade room on the right side of the map that's unlisted -- I don't know how to add an image here to show where it is so it's to the right of the top "blank" room on the right side just below the elevator.

The room marked secret has a switch in the blank room below it to open to get the key to fight the boss.

After boss room comes 2 more rooms

Great work! Thanks for that!