U Key Level

This level is found in P Level, called "Robot Climb Zone" in the code. It is cursed so you can't put items in your inventory.

First area: there are some Floating Blocks. They can be used to toggle floating on/off. Throw a few of them up in the area to make a "bridge" across to the door in the upper-right. You can jump on them momentarily to get across.

Next area: same idea to build a bridge across with Floating Blocks, except there's a green laser. Every time an object passes through the green laser it is "used"/toggled. So toggle the floating cubes off, then throw upwards so that they will be on after they pass through the laser.

Next area: a big pile of gems and a Virus item. When you push the virus into the gems, they become infected. Head upwards.

Next area: The Health Gun demonstrates how you can cure the virus and revert items to their original form. Use it on the upper left pile of virus blocks to get some bombs, which can be used to blow up the brick wall. Head upwards.

Next area: The Health Gun can be fired at the Heart to create a healing explosion (curing all the virus in the blast radius). Watch out for the gun firing at you. Grab the blue bird and use it to fly up to the next area.

Top area: The tall door on the left is a link back to the Save Room. Head through it once to permanently unlock a shortcut back to here. There is a pink laser, which you can only pass through if your Save Room collector queue is full (9 items). Push some of the treasures at the top of the screen into the Save Room collector until the laser turns off. Enter the door under the U Key sign.

The treasure available includes:
 * Cyan Gunman, Bomb, Electric Blue Cube, Remote Bomb, Purple Gunman
 * 5 Coin, Box containing activated Bomb, Bomb, Red Gun, Bomb, Heart
 * Silver Gem, Green Cube, Health Gun, Electric Red Cube, Bomb, Electric Red Cube, Bomb

Boss Fight
A flying boss opponent will fly around, dropping Health Gun-projectiles and Save Room collector queue items. Once it runs the Save Room collector queue down to zero, it can be destroyed by firing at it. It will drop a box with the U Key in it.

The boss room fight room is called "Dorte" in the save file.