Reviewed on request.
I don't see many tank levels around and would consider them to be almost as difficult to design well as underwater levels. This level does a lot of things well, while having these one or two things which drag it down for me. Let me go over the positives first though, because that's how I roll.
While the atmosphere in this level is nothing outstanding, it's exactly what it needs to be: A bit dreadful, dangerous, and definitely tense. The level throws a large array of obstacles at the player, ranging from cannons to lakitu, and it feels like the level is seperated into different sections giving each different obstacle its own time to shine. While one might argue this would make the level seem a bit jumpy and disharmonic, I think it works well in the context of a tank level, as it helps memorise the layout of each area in case the player dies, and makes them more memorable overall.
The enemy variety encompasses your standard arsenal type enemies, apart from maybe snifits or dry bones, though the focus seems to be largely on bullet bills. I think they're the most common enemy I found. As I don't have much more to say about "generally very good tank level type geometry and design" I'm gonna use this as a segway into the first issue I have: There's a bit of an unbalance resulting from the npc placement coupled with the fast autoscroll. I think if you slowed down the scrolling by ~0.3 and removed an enemy or two in largely cramped areas (cramped due to a lot of enemies) (example: you don't need two lakitus, 2 hammer bros and a dozen billy guns at the very end), the difficulty in this level would feel much more fair. As it stands now I often found myself in a position where I'd value taking a hit over risking to fall behind and hoping no difficult spot would come up until the next fire flower. Speaking of powerups, the way they're laid out makes progressing in the later parts of the level a bit frustrating if you're not a good player. I think the two fire flowers in the end section might aswell be moved to somewhere in the previous section where there's a particularly large gap between powerups.
The second issue I'm having is a technical one which you're not really at fault for. If you look at this gif:
http://i.imgur.com/7qFxvRS.gif
What I did was wait for 2 minutes for the autoscroll to progress on its own. This is an issue with internal smbx, I'm aware, but by injecting luna-steroids in form of a lunadll line or lunalua code which activates/simulates autoscroll once the player enters section 2, it can easily be fixed.
The last thing I want to address is more of an inconvenience rather than a real complaint. While I find the secret star to be a fair addition to the level, I think it's weird how the key is locked behind a keypad, creating an awkward yet easy escort mission for a 2nd key to open the keypad to get the door open with the other key. It just feels weird and could be pulled off in a more natural way with top-solid blocks, switches or even by omitting the key and keypad and just having the escort mission.
Overall this was a pretty good tank level. I like the way it was laid out and the secret star. While it doesn't do anything truly amazing, it's still overall enjoyable. The difficulty is a bit on the unfair side thanks to the fast autoscroll, to the point where you had to counterweigh it by using frequent powerup supply throughout the level. By slowing down the level and removing a hammer bro here and there, I feel like this could be easily fixed.
6.9/10
Moved to "pretty good".
At least put them in ?