"This gun would look pretty good against my head."
Assuming you don't quit and go for a relaxing nature walk, you restart and take the other direction at the fork. Down this road you'll find that the castle's stalwart defenders are protecting a wrench that's just lying around for no good reason.
The final boss is guarding a half-empty Mountain Dew and some Cheetos.
OK, now everything's falling into place. You get the gun, use the wrench to turn off the electricity, use the gun to kill the dragon ... and have your quest stopped dead by a locked door, the key to which is waaaaay back to the left of where you first started the game (that locked well you thought we forgot about was the exit). If you're wondering why the front door of the castle isn't locked, the only answer we can come up with is that the developers are a bunch of floppy dicks.