When escaping Castle Frankenstein on level 8, you will pass through 
familiar rooms. When you get to the room where you first encountered 
pygmy bats, jump through the hole in the wall in which you came through 
to get up there. As you jump down, you will notice a pool of spilled 
goo off to the side from one of the containers. If you look closely, 
a glowing lightning gun will be lying in it. Add it to your growing 
collection of superb weaponry.