KABOOM's KoopaCorp™
This level contains a good amount of platforming challenges of many kinds, as well as a block boss type section and a true/false pop quiz. It's got a bit of everything. It's like the Diversity maps for Minecraft in that aspect.
The office building premise is very interesting, and the various Koopa workers have nice dialogue, with some clever humor.
While the platforming sections are somewhat difficult, they aren't frustrating. They don't require milimetric precision, just knowing where to jump next.
All in all, this level isn't too exciting, but it's a fun level none the less, with something for everyone.
Fun: 7/10 ~ Varied gameplay in a clever setting.
Graphics: 3.5/5 ~ Nothing impressive, but it does the job well.
Other: 4.5/5 ~ Good premise, and the dialogue is funny.
Total Score: 15/20
Coinshower's Mushroom City
First off, I had to move the Start Position. Level Designers, please remember to put the Start Position at the beginning of the level when you're done testing. I didn't notice this the first time around.

Anyway, the level seems ok. The sign at the beginning didn't make sense to me (''Finally I'm out of that black hole! That level design was awful.''), but maybe this is part of a series... or something. I don't know.
The platforming was ok, but it wasn't that fun to traverse.
The graphics did the job, but they weren't too good. That beige block tile was just too used, and the place could easily be a desert ruin with a few houses around.
Also I don't understand the random pipe which sends you to a slingstar that hurts you when you land. It was odd.
The 5 star thing seemed like a neat idea, but sadly there's only 2 stars in the level. You probably didn't have enough time to do everything, I guess.
Fun: 4/10 ~ Could have been much better.
Graphics: 2/5 ~ Cities aren't made of beige bricks

Other: 3/5 ~ The 4th wall joke was kinda nice, I guess?
Total Score: 9/20
1018peter's Primetal City
I'll start by saying THIS LEVEL IS HARD
In the first level, the bottom path seems almost impossible to pull off, I couldn't do it myself... the top path is more sensible though. One problem that I saw is that for the most part if you fall off the top path, it is possible to backtrack in the first area but real hard to do, you need to get to the end of the area and backtrack from there, looks hard as hell but not impossible. However... if you fall off later it seems impossible to backtrack. So if you fall off the top path there you might as well start over.
The graphics are superb. Looks great, tiles are varied and whatnot. The only issue I see is that it's difficult to tell apart the background tiles from the other tiles at times, especially if you don't know all the tiles in the designer too well. But besides that it looks awesome.
The platforming is... difficult. But it's consistently difficult, so I know that was the intention. I might not be able to do it on one go but maybe some MLG pro around can

But there is the issue of it being somewhat confusing at times, not to mention that you really need to zoom out to see what's happening. But all in all, it's good.
In the second level, the Race Against The Flames is too hard. It requires too much precision, and slowing down just a bit results in death by tons of flames. Even when you know the layout it's hard to get it right. The hardest part are the switch-activated platforms.
At least there's a checkpoint after it. c:
The Magmadon battle is kind of laggy. It's not bad, but doing the same climb three times can be a bit frustrating, considering all the fire there is.
The Big Bob-Omb battle is quite hard, but I like the idea of it.
Also, the platforming overall in this level is easier than in the first one. Huh.
Fun: 7/10 ~ That is, if you can stand the heat...
Graphics: 4/5 ~ Very good in the first level, it kind of degrades a bit in the second one though.
Other: 3.5/5 ~ There's many creative ideas, but it also has lag at parts and it can be unfairly difficult.
Final Score: 14.5/20
Supershroom's Futuristic Dream
Ok let's discuss gameplay first.
The gameplay for the most part is average. It does its job, but there's nothing particularly interesting about it, and the difficulty is easy. However there are parts where the difficulty rapidly spikes, leading to areas such as the wing cap flight, and the Daredevil challenge. If an element of the level required you to make a walkthrough of it, something is wrong. Especially considering that most of the level isn't as hard as this.
The first level is confusing to navigate, especially since it's possible to skip certain sections, which makes it harder to obtain all of the red coins needed to end the level.
Also, you don't tell us that we can bounce higher in the trampolines by pressing up when landing on them. Not knowing this makes it impossible to go through some sections.
I also find it weird that the second level doesn't have any checkpoints, but the third one does. Then again, it does have the Daredevil challenge.
The Final Boss (The Wall) was ok I guess. I kept dying to it, but I'll attribute that to me sucking at this game. It doesn't seem unfair.
Graphics, I don't need to say anything. The thing's great. It suffers at places of the same problem of Peter's level, but to a lesser extent. For the most part everything can be told apart. However it's so great that it causes lag, and it takes forever for the code to load. And that substracts from Fun.
Now, the story. I appreciate the fact you're telling a story, and here in Runouw we're kind of suckers for that type of thing, but I can't help but feel the story doesn't... match the genre. You seem to be telling an epic that would probably fit better in an RPG. not saying that platformers can't have good story but here you're trying to explore a world. And there's just so much you can do here. And while you do present the world to us via, well, graphics, this leads to making a lot of the gameplay somewhat uninteresting. This won't take any points from Fun, and I'll give you a bit in Other for trying to make a story. Also, I spotted some grammar errors here and there, but I'll let it slide.

...Also, you killed MP3. You ♥♥♥♥♥♥♥.

At least it was just a dream.
Fun: 5/10 ~ Inconsistent difficulty and nothing too interesting in terms of platforming.
Graphics: 5/5 ~ Nothing to say.
Other: 4/5 ~ Story and a lot of thingies. It has lag though...
Final Score: 14/20
Final Results
1st ~ KABOOM's KoopaCorp™
2nd ~ 1018peter's Primetal City
3rd ~ Supershroom's Futuristic Dream
4th ~ Coinshower's Mushroom City
9th ~ Yurimaster's ElectriCITY
10th ~ Star king's Glitch Castle III
11th ~ TripleJ's City of Old Streets
12th ~ ~MP3 Amplifier~ and *Emelia K. Fletcher's Sonata For A Minor
13th ~ NanTheDark's "Soon"