So here we are at Mega Man 4. It's got a nice intro showing us the story thus far, another round of silly Robot Masters to fight, and a new mysterious villain. Nowadays, this one is often considered the turning point of the series' quality, so let's see if there's any truth in that.
We start by meeting the new enemies in this section separately. The first is Swallown, with three Coswallowns following it. Swallown moves across the screen slowly, and it sends the Coswallowns toward Mega Man after it is killed (two shots) or when it gets close enough. The first one comes in at a good position to give players a shot at the little ones, while offering room to dodge if they miss. Next up is Rackaser, who drifts down from the top of the screen, then throws his umbrella and walks forward after landing. He takes four hits, so he requires some attention if you want to take him out before he lands, though the umbrella can be destroyed with one shot.
These also help introduce the environmental effect in this area by encouraging players to jump, during which they'll discover that the rain here pushes Mega Man back a little while he's in the air. Both enemies appear together from now on, first at Mega Man's height making them easy to gun down, then out of reach.
Now pits are involved, and with the rain hindering Mega Man's forward movement, even these small ones can be a challenge. The second is the hardest of them, requiring Mega Man to be partially off the platform before jumping. Rush Coil is back to help in such situations, though the Swallowns may need to be dealt with first. This is a great section, with two complex enemies competing for the player's attention and a few difficult jumps.
Dropping into the sewers gives us the opposite problem, with running water messing with our movement on the ground. Two new enemies, Ratton and Puyoyon, appear here. The former simply jumps forward now and then, while the latter oozes around on the ceiling and drops when Mega Man gets close. Both take two shots, and can be cleared without much trouble by just shooting constantly while running through here.
The waterfall restricts Mega Man's jump height, while also providing cover for a nearby Ratton. The following Puyoyon will likely fall on the lower platform and get in our way, but the gap here gives players an alternate way to deal with it by luring it underneath.
Finishing this up brings us to another drop with a safe ledge, and this is as good a time as any to show off Mega Man's new ability. Holding the B button allows Mega Man to charge up a shot that deals three damage and moves through enemies it can kill as well as causing a bit of recoil, with a partial charge firing a smaller shot that deals no more damage than a normal one. The enemies in the first section offer good targets for this, as it can fire through the birds or hit both a Rackaser and its umbrella. The next screen shows us another way this was incorporated into the game's design.
Unfortunately, the charge also comes with a sound effect that persists for as long as we're holding it. It's not so powerful that we'd need to be holding one all the time though.
Escaroo here can detach his eyes and send them after us, or fire bombs from his shell. He takes 16 hits to kill, but he only takes damage in the eyes, and only when they're open. This gives us a small window in which to attack him, making it worthwhile to have a charge ready. This isn't entirely stacked in favor of the charge though, as we still have just enough time to get two jump's worth of shots in, and we can't always have another charge ready between periods of vulnerability, so firing normally is still a valid tactic. It's a good fight, giving players the opportunity to make use of all of their abilities.
The next screen offers a way to bypass the enemy at the bottom, though a single Ratton isn't worth making a shortcut for. We're then thrown into another Escaroo fight, this time with a waterfall in the middle. The flowing water makes dodging more difficult, and while we can stand still in the waterfall, we can't jump high enough to get hits in. Though they could have spread these out more, it's nice to see an extra hazard added to the second one. After that, we run into a fish-infested water area with small platforms above it, which should look familiar.
Unlike Gemini Man's stage, we only have one enemy to deal with and the platforms are more forgiving. Gyotot jumps in an arc and can be killed in one hit, but we don't always have a good shot at him. The jump between the fourth and fifth screenshots here is particularly harrowing, as the Gyotot will jump just as we're trying to land. He'll miss if we keep moving forward, or we could use Rush Coil to reach the upper platform. It's also nice that we have to enter the water briefly this time.
This has all the makings of a good stage. The enemies are appropriate for each area, the miniboss fights are solid, there's a good mix of fighting, platforming, and environmental effects, and the stage gives a strong impression of moving through a real place as well as being a sewer level that's pleasing to the eye. However, the ease of the Rattons and Puyoyons makes the middle section fall a little flat, particularly when bookended by the more difficult first section and Escaroos. It needed a little more bite, but it's at least interesting to run through and makes for a great starting level, even more so when we consider the ease of Toad Man himself.