Dr. Wily Stage 1 and its music. Again, now that we're at the Wily stages, things have changed a little. We have all the weapons, and it can be assumed that we have some idea of what we're doing by now, so the stages should be designed with this in mind.
Pipi starts flying in after our first few steps, and a few screens later we find ourselves blocked a wall too high to jump over.
This forces the player to learn how items work if they haven't yet, and any of the three will do.
Next up is a few Scworms, another wall, and yet another chance to use the Items. I'm using Item 1 here because I wanted to, but this is one of the few places where Item 3 has a purpose since it won't fade out on the way up.
The following screens have a couple Joes above us. The terrain gives us no chance to dodge their projectiles, but they can be taken out from below with a variety of weapons. There's a Springer waiting at the top of the ladder, and the large gap above forces the player to learn that multiple Item 1's can exist on the screen.
After a couple Tellys that we can climb right past, we finally make it inside Wily's fortress. I like the transition here.
All of a sudden the jumps get very dangerous, the game switches over to autoscroll, and a freaking robot dragon warps in and explodes us with his face. I have two problems with this. First, the autoscroll kicks in between two specific platforms, and is very jarring if you're not expecting it. I'd have preferred one more long platform in the spot where that happens, which would also break up all the single blocks a bit more. Second, the dragon is an instant kill (even if it wasn't, the hitstun would kill you) and it takes up half the screen. There's not much room for error once the autoscroll starts, so any delay is likely to result in a death. It's terrifying and memorable, sure, but it's also a cheap shot.
Once we make it to the last three platforms and the fight starts, things go smoother. Mecha Dragon shoots fireballs at random intervals, and occasionally launches a long string of them that causes a great deal of flicker, since the dragon itself is already pushing the poor system to its limits. One other thing to watch out for is that the hitbox on the dragon's head is a rectangle that takes up the space between its horns and nose, causing my death here. It's annoying, but the chances of it happening are fairly low since Mecha Dragon doesn't end up in that spot often.
Anyway, the fight's still a lot of fun. Standing on top is the safe option, since any hit will just knock you to the lower platform. However, unlike the main bosses, Mecha Dragon has no on-hit invincibility, so you're free to kill him as fast as you can shoot, making jumping to the lower platforms worth the risk if you want to take him down fast. Quick Boomerangs deal the same damage as your buster and can be easier to hit with, and a charged Atomic Fire will take off a third of its health. There's plenty of time to charge on the way in, so you might as well go for it.
I'm tempted to complain about how little challenge the stage offers and how short it is, but Mecha Dragon is difficult enough at first that I could understand why the designers may not have wanted to force the player through a longer and more dangerous stage beforehand. It could have used some other enemies in the first section alongside the Pipis and Scworms, but these and the enemies above you in the middle part are all a hassle to kill with the Buster alone, so the whole thing is really just there to encourage the player to start using weapons during the stages if they haven't yet.
The music is one of the most memorable from the series and the visuals give a solid impression of climbing into a real place, but I've never liked the artwork here much. It doesn't have that outlandish feel that the rest of the game did, instead reminding me of the nondescript military compounds that show up in various Contra-likes.