Stunning. The graphics, while simple, are a huge upgrade from this game's sequel. I would have liked an option to switch to low quality, though, since the particle effects have a tendency to lag really badly (I wouldn't have minded switching back to high quality to read the dialogue). Another thing is that I accidentally finished a bunch of levels too quickly, before I had read all of the dialogue, when boxes popped up just as I was about to beat a level. An option to reread dialogue would have been nice. Other than that this game looks great! The textures look spot-on and the sound effects are satisfying, too. Working your ass off for that satisfying clicking noise that means you just hit the right switch makes it all worth it.
The gameplay is excellent and reminds me a bit of Spewer. Implementing the mouse for both sprays and for smoke rings add a lot of replay value, especially with the whole teamwork thing. The difficulty curve is nice and smooth, albeit with a couple bumps, and I found this fun to play and experience.
One thing I'd point out (and I'm sure people will complain about this a lot) is the brutal difficulty. I think it might be nice to be able to skip certain levels (and see the dialogue so you don't miss out), and then be able to go back to it later. Perhaps a simple system like allowing one skipped level at a time would have allowed players to get better at the game in order to go back and solve puzzles on their own. As it was, I did have to look at a walkthrough for 5 or 6 of the levels.
I'd also like to congratulate Carney for composing great music once again! Both the original pieces and rehashes sound excellent and really drew me into the mood. You've got a brilliant storyline going here and this prequel did not disappoint. This easily deserves a 5/5.