I love what you created here. It's a fun, yet difficult game with a lot of charm.
The design is excellent. The little people running around look like a cross between 60's design and that overdone modern corporate style, and I think it looks great. The eye at the top is direct and on the nose and fits in perfectly.
Music is pretty good too, although I feel it could be a little darker sounding in the part with the rain, as it tonally still sound a bit to cheery. Sound design is great, I like how everything has a little variety. Just a suggestion, maybe add a quick, deeper reverberating sound when you get replaced (as you get shot, before the glitchy sounds that continue for a few seconds) , something to add a bit more impact to the loss.
The film grain, muted colors and rain effects in the second area of the game makes it really frustrating because of how all the colors blend together. I'm not colorblind, and even still, it is really difficult to tell the colors apart, especially when they all bunch together as a writhing mass. I had no issue with the first area, as all the colors are easily discernable from each other, but I never could pass the second area. That was where I called it quits. When designing a game, it's recommended that when a player fails, it feels like their fault, but with how hard it is to tell colors apart in that area, it feels like the game is the issue. I see how you were trying to create an atmosphere, but I think it was overdone for a mostly casual game.
Also I was mildly confused at the start of the game. I see what you were going for with clicking a person to start the game (and register a mouse input), but I think a standard "start" button would be a better choice. When clicking the start button, it could just vaporize the person from above, both showing the core mechanic of the game and have a nice transition. Sometimes a simpler menu is a better option. Your call though.