The first screens of this stage give us a robot seal called Au-Au who balances an energy ball on its nose before throwing it at us.
Read that again. I just want to draw extra attention to how ridiculous and adorable that is before I move on. Cool? Cool.
As an intro segment, this area does its job well. We've got two types of enemies, an explosive bomb platform with a timer that counts down once we step on it, and two types of terrain, with the solid ice being slippery in the same way video game ice always is.
Au-Au can throw at a few different angles, but the one shown in the last image is the lowest, so they're not that dangerous up close, and it's even possible to stand next to them safely. It works as a good misdirection for the player though, as I think most would react to an enemy like this by backing up to prepare to dodge whatever it does, putting them in a better position to get hit.
So... there's a lot happening here. The timed platforms aren't required yet, but we now have the option of jumping a series of them to reach an upper path with a health refill. The upper path also introduces sideways versions that we need to press against to activate, then back off to avoid the explosion. There's no real challenge there, but we need to know this for later and the slippery floor at least makes it a little awkward.
The new enemy on the lower path, Teck, has a somewhat unique behavior for a turret enemy. It will walk toward the player until it's a certain distance away, then shoots downward continuously unless the player moves out of range. The distance it chooses is just right for catching a player trying to run or slide past it depending on height, meaning the best solution for avoiding it isn't always the same. It's easy enough to kill, but this is the kind of thing that works great when paired with other enemies, or just to trip up anyone trying to speed through the game.
The ice pillars blocking the extra life can be destroyed with Flame Man's weapon, and this answers something I almost complained about on the previous screen. See, the energy refill seemed odd, as there's not much chance the player would be low on anything yet. However, the boss here is weak to fire (naturally) so anyone stopping to get this might want to top off the weapon's energy before moving on, which means walking back a screen. This gives Au-Au, who we won't see again in this stage, one last chance to shine. When approached from behind, one will be slightly above the player and the other below, which is a more dangerous position than the first two encounters. The Jet Armor is needed to get the item and can be used to fly over the Au-Au's, but their higher shot angles make this dangerous as well, and it feels like this specific situation is the only reason they can shoot upward at all.
Another thing I love here is that first Propeller Eye, as its position is perfect for making every approach variation fun. A player could immediately jump to the first timed platform and destroy it with enough time to move on, a more careful player could stop and kill it from the snow, it's just close enough for the Power Armor to punch mid-jump without stopping, and just far enough for Jet Armor to barely make it to the second platform from the snow before it attacks. It's even high enough to run under, in case a player jumps to the first platform, sees the rest and goes nope, and just keeps walking. Great enemy.
Pressing to the left at the drop gives the player a chance at an extra life hidden in the cracked block, and the Eye here makes this a little difficult to do without getting shoved off. The next new enemy, Curlinger, slides along the ground like one would expect from the name. Punching it with the Power Armor causes it to slam against the opposite wall. This is one of the coolest things one can do with that ability, and luckily this area gives us good reason to leave it equipped, as the next coolest thing is being able to punch right through the new Shield Attacker.
If you don't have the Power Armor, or for some reason just don't want to do that, the Shield Attackers are all high enough to slide under, which is quite fun to attempt when they're all crammed together at the end. The cracked block contains a large health pickup, but breaking it gives the final Shield Attacker more room to move. The E-Tank here gives us another opportunity to waste Flame Blast ammo. This may be nothing like the choice between using Flash Stopper in either Quick Man's stage or the boss fight, but at least it might get the player thinking about looking for a refill.
After this we meet Squidon, which is one of the better large-but-not-quite-midboss enemies. It spits sliding ice cubes and fires homing missiles, and we can approach it by fighting at range to give us more room to dodge, or running next to it and shooting through the ice to kill it quickly. I like that it rewards boldness or precision dodging, as the projectiles come out quickly enough to discourage trying to shoot them all down.
This area's gimmick is a large submarine that moves up and down, alternately threatening to drop us on the spikes below or crush us against the ones above. Most of the area is safe to stand on, but we need to fight Cannon Joe along the way, who just sits in place and shoots at us.
The sub's movement makes this more interesting than it sounds, as everything is moving up and down relative to the projectiles, meaning the incoming shots might not go where we expect, and we can even aim our own from different elevations to attack safely. The blocks here don't contain any items, but removing them can make this area a little easier.
The last section of the sub contains a short path to an E-Tank, which is underwater half the time. I appreciate that we have enough time to grab it without sliding, so we don't need to switch armors again after punching the block, or to navigate the spikes above, for that matter. Finally, the explosive platforms become mandatory, with a line of them leading to the ladder. Of course, the Jet Armor can make this much easier.
After a practically empty room, we come to a second fight with Squidon, made harder with a little more height and less room to stand in front of him. The open space also makes the Jet Armor more viable.
The final screen involves making a few harrowing jumps to set off the two bombs in front of the boss door, but we can make this much easier with the Jet Armor and even flying right under the whole mess. Another nice thing about the last bombs is that the explosion is short enough to be avoided with a jump, meaning we can press against the first one while jumping on top of it, then stay there and avoid the blasts to reach the door instead of jumping back to the ice each time.
On a content/space ratio, this stage is incredible. It has a large variety of challenges to juggle and somehow gives them all enough time to shine. The bomb platforms give us a few screens to play with them before jumping a row of them and carefully setting off a couple from a small platform.
The submarine flows very quickly from the first screen with a floating piece of ice that stops its gimmick from killing us, to fighting enemies with a low spike ceiling, a few deadly holes, and awkward shot movement, to timing a run through a tight corridor for an E-Tank and navigating between a few holes in the spikes. Meanwhile, it offers fun uses for both new armors everywhere, and includes specific areas that feel built for both. The Power Armor can punch its way through Curlinger and Shield Attacker, and the Jet Armor can bypass most of the final platforms with the opportunity for a nice aerial battle against Squidon. All three armors are also viable and fun if left equipped the whole way through.
The only thing I can complain about is the last indoor screen, which just doesn't have anything to offer. Despite that, this fits so much good stuff into the space it has that I've had to rewrite this a few times attempting to catch everything worth talking about.