
Stage 5 is the final level of the game, and definitely the most gruelling. The action starts on the roof for no discernible reason, and as you fight off the big-headed riflemen and the cannon midgets again, something starts to happen- the castle is falling apart?! The game speeds up a bit as Edward apparently tries to avoid falling, only to be attacked by obese bats. There's no explanation as to why the castle is crumbling, and it's never mentioned or referred to again. It just seems to be there because it looks cool. A perfect design philosophy!

At the end, a door back inside the castle explodes, giving us Inexplicable Explosion #5.

The final normal section of the game is also the longest, but at least there's plenty of things to shoot. It's a secret laboratory of some description (because, as we all know, all castles have to have laboratories in them. Always. Every single time) and we meet the final two enemies of the game, both of which who only ever attack you from the background, and never get up-close and personal. The first new foe is the psychic mutant with weird metal things on his head, possibly to keep the FBI from stealing his thoughts. They'll launch electric blasts at you that move slowly towards the screen, but they move about erratically, so they're slightly harder to shoot than the other projectiles in the game. After taking a shot at you, though, they'll disappear off screen, so catching a glimpse of one is surprisingly difficult.
The other new enemy is the brain pod thing, contained in a glass chamber. You can shoot the chamber all you like, but they'll only explode when the brain pods want to come out and play. These things aren't much of a threat at all, as they only take one shot to kill, and they potter around the screen for ages before using their only attack- the same thunder projectile as the psychic mutants. Shoot them before they become a problem.
Anyway, there really isn't much to say about this section. It goes on for ages, but the new enemies make it a little more interesting, and there's a lot of background items to shoot- glasses, wardrobes, giant machines, and all sorts of things that reveal goodies for you to pick up. Keep it up, and you'll eventually wind up in front of an out-of-place door...

Hey, it's the spirit that flew out of Charles when we killed him! Looks like he's back for Round 2.

Actually, an indestructible body wouldn't be too bad, if I'm honest... It'd save on all these continues I keep having to pay for.

I said 'no' without even moving my mouth. Let's get this over with.

Charles' second form is infinitely more annoying than his first. He may only have three different attacks, but that doesn't make him any less of a threat. He can throw two different projectiles at you- either a glob of phlegm or a fire-ball which is actually pretty slow- and he can also bite you. Unlike every boss you've fought so far, his biting attack is, as far as I can tell, unavoidable. He can't be shot enough times to make it stop, and shooting anywhere else does nothing! So how do you beat him? Shooting either of his two heads won't do you any good, as while they'll (eventually) explode, they come back only a few seconds later. Shooting the rest of his body doesn't do much- what is a miserable detective to do?
The answer lies in Charles' belly button- it's an eye! It'll open up every now and then, and this is his only weak point, so concentrate your fire there, and take out the projectiles when they show up. Fortunately, it takes a lot less bullets to kill Charles than most of the other bosses, so you should finish him off pretty easily. Quite fitting that he's the last boss, is it not? Now, how about an ending?

Wait, what?!?

Well, this is a bit of a kick in the teeth. If you were playing this in an arcade, you'd be pretty pissed off by now.
This is what most of the foreshadowing has been pointing towards (well, the foreshadowing that wasn't along the lines of 'Ha ha ha, Charles is a bad guy and he screams like a girl')- there's three crystals hidden in the game, and you need to find them to get the real ending. Otherwise, you'll spring the trap door after beating Charles again, and lead Edward to an early grave. Again, the way to find the crystals was posted by an unknown player on arcade-history.com, without whom we wouldn't have been able to finish this game at all. We thank you, unidentified player. We'd better head back to the start and find these crystals, then...

Lucky for us, we don't have to go too far back. The Red Crystal is found at the end of Stage 3, when the zombies pour out of the elevator. Remember, this was the closest Stage 3 got to a 'boss encounter', and it's technically optional, as the zombies will walk off screen if you wait long enough. If you want the crystal, though, you have to kill all the zombies here and it'll appear before you- shoot it and you get a short little cut scene once the stage is over...

"What is this?"
A mystery indeed, Edward! Collecting this first crystal adds a counter on the end-of-level score screen, tracking your crystal progress.

The Blue Crystal is hidden in Stage 4, in the section with the werewolves after the fight on the banister. There's a series of weird statues in the background, and one of them is actually the demon statue that we saw on the gate in Stage 2. You'll need to find this statue and destroy it to uncover the Blue Crystal, then shoot it to pick it up.

Fortunately, the Green Crystal is given to you automatically- just beat the boss on Stage 5 with the Red and Blue Crystals in your possession to get it. Time for us to face the final boss and sock it to 'im!

Huh? No-one said anything about a correct combination! You sold me out, mysterious final boss!

So wait, is this Charles helping us out from beyond the grave? Despite the fact that we've filled him with bullets not once, but twice by this point?!
Whatever, we'd better give this the old college try.

Uhm... Let's see... I've only got 10 seconds?! Screw it, let's just have a wild stab at it.

Blue, Red, Green. Seems like a good enough answer to me.

Dammit, not again!

Thanks for letting me know, you jerk.

Of course, if you're not completely brain-dead, you should've figured out by this point that the game doesn't force you to figure the combination out by yourself. The demon statues on Stage 2 and Stage 4 show the correct order of the crystals- Red, Green, Blue. Shoot the crystals in this order, and the door will open... Or, rather, it'll explode, which gives us Inexplicable Explosion #6. Yay!
The final boss is close... Let's go through the door!