What a nice little chapter you've got here! The sandmobile is really nice, even if it does have a bit of trouble backing out of tight spaces (though it's my fault for trying to squeeze it into small spaces in the first place xD), and all of the challenges are compact enough to not feel bloated yet still be satisfying. The little descriptions for each level on the act select screen fit right in with the game; I especially loved Hat Kid's comment on how she needs the Dweller's Mask for freaking everything. The dialogue was all entertaining, too. I might have related a bit TOO hard to the shut-in stuck outside, and I also go to do this.

Your original music is all very groovy; I really like the unique percussion in some of the tracks. (There seems to be an issue with selecting Hopeless and Default Songs from the jukebox, though.) Speaking of music, it's great to see DJ Grooves get a little love! The Conductor is easily the more popular of the two (and don't get me wrong, I love my angry Scottish bird[?]), so seeing him pop up put a smile on my face.

Now for the less fun stuff: a few problems with the level.

I had two issues in the Time Rift near the race. One, the camera kept weirding out in the last "climb the spinning platforms" section (and I swear I teleported a few times when jumping to the end of a platform) before the Time Piece, which made it a lot more difficult to complete. And two, if you get the Rift Token in the same rift, you'll still be stuck in the animation when the platform falls (unless you button mash out of it, maybe? I was too dead to check).

Finally, the finale was underwhelming (spoilers for those who haven’t played it yet). What made The Illness Has Spread work despite not being a boss is that it was a challenging obstacle course. The much more open nature of this chapter doesn't work well with that, even with the buzzsaws, which serve as more of a hindrance than real obstacles. (I also found it odd I couldn't drive through the circles in the middle of said buzzsaws without taking damage. Also, why buzzsaws, exactly?) Admittedly, I'm not entirely sure how this could be fixed because my level design skills are... lacking, but if you ever consider working on this mod again, take a good look at The Illness Has Spread for ideas.

One other small thing: I'd prefer it if you spawned back in the mail room instead of the boiler room to make it easier to get back into the chapter after a rift. Plus, it seems at least one person has had an issue with being spawned in an area they haven't unlocked, so it'd be convenient for them, too.

Overall, it's a good level that fits right in with the rest of the game despite its issues. The various environments keep what would have otherwise been a stale desert theme fresh, the level design fits this game to a T, and the dialogue ties it all together with a nice little bow. Thumbs-up from me!

(I was originally going to post this as a comment, but it turns out comments need to be under 1,000 characters. Oops.)