It is a very enjoyable game with retro music and pixel style graphics.
Killed all the enemies on the first floor, collected 4/4 gold balls in about 10 minutes. Then glitched through to the second floor.
Found no bugs other than some (maybe intentional) graphical glitches here and there, like vertical white lines between the tiles and some black rectangles flashing randomly. I'm not sure whether they were intentional.
I think the map should show the doors as connections between the rooms. It would allow the player to see where are undiscovered rooms.
Robots were too easy to kill.
All in all, it has been the best entry I have played so far. Congratulations!