Well, not “kill” because he’s already dead, but it was about as satisfying.

From Mobygames.
I left off last time giving Hitler a piece of some sort of crucial magical object. As Beelzebub indicated earlier, however,
WHEN DEECULA IS RESTORED AND IT’S POWER GLOWS, THE CRYSTAL SEALS HIS FATE.
The crystal is going to come up fairly shortly.
After the scene with Happy followed by Raging Hitler, his goons tossed me down a slide and onto a pillar which was slowly lowering while being surrounded by giant spiders.
The pillar had a “beam of light” and I was able to look up to see a hook and an opening. I had fortunately grabbed the chain I had used earlier to clamber up to the Hitler Area so I threw that up and caught the hook, and was able to climb to safety.
This led to an vent with a wall covered by a canvas. I used the dagger (which was randomly stuck in a door from last time) to cut through and find a giant crystal with a slot. At the same time I collected the dagger I had collected a sword with blue jewels in it, and it seemed about the right size, so I did some reverse Sword in the Stone action:
Crystal in hand, I went down farther in the vent and found a grate I was able to push open leading to Hitler’s office. Crawling in led to, well, let me just show you:
Notice: “stunned”. Hitler had a crown on him which I yoinked, and I was able to retrace my steps all the way back to John Wilkes Booth and Satan’s room, but John Wilkes Booth was now gone.

Technical aside: on the Apple II version you need to sometimes swap disks. The Hitler area required a disk swap, as does walking through this door. There’s still a decent amount of back-and-forth with already visited locations so this isn’t a scenario where the game is neatly partitioned off. Unfortunately, on the emulator I was using (AppleWin) I wasn’t getting any kind of disk swap message and the game locked up instead, so the only way I could keep playing was to swap the disk before entering one of the thresholds (either hopping from disk 1 to 2 or vice versa). Having to anticipate swaps wasn’t part of the original experience but I figured someone in the future might want to re-trace my steps and would like the locking-up mystery resolved.
Exploring farther, I found a giant snake that wanted the crystal. Dropping the crystal led to the snake swallowing it.

You still need the crystal. I’ve always liked the puzzle structure of an item getting lost that needs to be retrieved. It gives sort of a liveliness and dynamism to what normally are static tools.
Incidentally, I tried to KILL SNAKE after the crystal-swallowing scene and was told I didn’t have the right weapon (the dagger doesn’t work), which was a custom message. I mentally marked the location to return to later.
Just above the snake was an unpassable fire.
After some experimentation (and realizing I wasn’t getting through) I figured now was the time to re-re-re-visit ever location to see if a new item had popped up (like when the dagger appeared).
Fortunately, it didn’t take too long to find something new, as shown above. That valve wasn’t visible before! Turning the valve and rushing back (remembering to swap disks yet again) I found that the fire was off.
The Black Mass looks pretty metal, although if you try to talk you get “slain for sacrilege”. Ow.
Here I was stuck a very long time — I could refer to the pews but couldn’t see anything, and started to get the strong intuition that I was just getting stymied by the parser. I took a hint, which told me to SIT DOWN. (I had unsuccessfully tried SIT earlier, so yes, parser issues. What made this spot doubly galling is the parser quite often lets you use verbs without nouns and you can even inadvertently hit a puzzle solve by just testing verbs alone.)
Moving on! The right action here is to PUSH the door (another tough one to find, although it is drawn with no handle) which leads down to a corpse-ridden basement with silver coins and candles with a ball of WAX. There’s also a crystal door with a slot…
…and this was the moment I realized I needed the crystal back.
The WAX needs to be melted, but there is weirdly a shortage of hot things in hell. I originally tried tossing the WAX in at the flames at the very beginning (where the LUCIFAGE keyword was shown) but was rebuffed. I had just recently found a fire I could turn off and on, though! I delivered the wax to the fire-grate room, went back to the valve, cranked the valve up, checked the fire room again, and found a CLUB. (You need to make one more circle to turn the valve back off.)
The CLUB, of course, counts as a weapon, and I already knew I needed one for the snake.
Did I do it … wrong? I wasn’t sure if it was destroyed, but I thought perhaps I could hike all the way back to the original big crystal and cut off another chunk somehow.
One hike across the map later (although to be honest, it still isn’t a big map) and I found what turned out to be the original crystal returned to where I found it. Nabbing it and hiking all the way back — past the bat cave, past the entrance to Satan’s area, past the Black Mass — and finally used it on the slot that needed a crystal. This pulled me into a black forest.
A maze! So exciting!
I mean, a maze, ick. Fortunately not a complicated one. While I mapped it already, I think this is a good spot to stop, although a brief preview:

Jesus, hanging out in hell.
So close I can taste it. Almost certainly next time for the (apocalyptic?) conclusion!
…gosh, the Third Reich’s a bit rubbish. I think I’ll kill the Führer.
The screenshot just after “Just above the snake was an unpassable fire” is making me laugh way too much because the text on it just says “Okay” (I assume this was the game confirming your previous action), and it has such “This is fine” energy.
I’m a tad puzzled that turning a valve turns off the fire. Hell has natural gas fireplaces?
You’d think these guys would be into sacrilege! I guess they can dish it out but they can’t take it.
Isn’t it (semi?-)canon that Jesus did go to Hell?
Hell used to use coal but switched over sometime in the 90s.
Jesus visiting hell is sort of considered implied here: 1 Peter 4:6. For this is the reason the gospel was preached even to those who are now dead, so that they might be judged according to human standards in regard to the body, but live according to God in regard to the spirit.
And in the Inferno, Jesus is explicitly said to have come to Hell to save a lot of Old Testament figures:
“I was a novice in this state,
When I saw hither come a Mighty One,
With sign of victory incoronate.
Hence he drew forth the shade of the First Parent,
And that of his son Abel, and of Noah,
Of Moses the lawgiver, and the obedient
Abraham, patriarch, and David, king,
Israel with his father and his children,
And Rachel, for whose sake he did so much,
And others many, and he made them blessed;
And thou must know, that earlier than these
Never were any human spirits saved.”
According to the Wiki of The Harrowing of Hell, the Apostles’ Creed and the Athanasian Creed both mention Jesus’s descent to Hell, though not the saving souls part. I guess the creeds may be canon even if the Inferno is influential fanfic. (Not canon in the technical sense, maybe?)
“The Black Mass looks pretty metal, although if you try to talk you get ‘slain for sacrilege’. Ow.”
They’ve got pretty good taste in metal in that case:
Also, why Lee [Harvey, presumably] Oswald? He’s no charismatic villain, he’s just some two-bit assassin who got lucky, definitely not a great enough orator for a black mass. Might as well have Charles J. Guiteau (Garfield’s assassin) instead. Now that would be a sight to see.