This is one of the more unusual hacks on the site. It involves puzzle gimmicks made using strange blocks frequently throughout each level, although Mt. Maze is the one level free of them and focuses more on platforming. There is no item babysitting in this hack, which is probably relieving news to many puzzle fans.
The Infection has an unusual story and its progression is shown through overworld events making the problem bigger and bigger with each level you beat: a plague of colorlessness is spreading across the world. In fact, it sounds almost like a certain mime from an episode of The Powerpuff Girls, but I don't think crayons and love and music are going to be what stops this disease. (Oh, and there are areas you play without music "because trust me, you'd thank me later" - and the hack has a sense of humor about it.)
An explanation level shows you in an example level how each block works without giving you a verbal rundown of each item so it gets over and done with fast. After that, it throws you into the thick of it.
Even though there's a lot of stuff going on and much of it is recurrent, all of the levels feel different. Underground Trials is my favorite level because the enemies control the form of blocks in the environment by walking on and off of P-switches.
Some levels have missing or incorrect Map16 tiles in places - the most standout example I can think of is Mt. Maze.
There's a big problem I'm running into with the level "Hurry Up!" - no matter how fast I beat it, even with 55 seconds remaining in the first room (way before the song loops,) it does not let me go to Bowser's Castle. The overworld says it's supposed to and I can only guess that this is a problem with the goal blocks in this level. Furthermore, the readme isn't transparent on how to correctly get the exit (if it even works.) I want to know if this is just on my end - if it is, then the correct number of exits will be 9.
Also rather serious and prominent in the first level are areas you can get stuck in and be forced to die.
But, by far the biggest problem is the midway point in Stormy Fortress because you are dumped into the middle of a square of lava and dropped onto layer 2 spikes instantly and in order to progress, you have to deplete your stock of lives and get a game over to reset the midway point.
The hack edges on normal and hard. It's a shame there's all these problems present, because I find the level design enjoyable. It's got the hallmark of a curious 2008 hack where blocks fascinated hack makers and they'd throw a bunch in and end up with weird nonsensical hacks, only this one seems more well-put together than its brothers that pissed off many a Let's Player.