Yet another walk-through. This one will help you finish the game.

Fortunately, I had a saved game at the start of this level, so I got to begin with my full complement of weapons.

The key to this level is to find the path of least resistance. For example, it is suicide to charge into the room directly across from the starting point without softening up the resistance. This can be done while invulnerable from behind the cage protecting the blue key. See the demo for details and for other examples.

After collecting the red key, I proceed to the red door but do not enter, because the boss is in "easy mode" due to the nine hour bug. See L27Ace for a demo showing how to beat the boss when not in this mode.