The graphics are starkly utilitarian. Everything is drab grey, with important objects labeled in bright colors. The most prominent color, probably intentionally, is the blood-red that fills the borders and the HUD-text. Important objects that the player can pick up and use, including handguns, switches, keys, and so forth, are colored bright yellow.
The game is mind-bending not only because some of the puzzles, especially in later levels, require lots of lateral thinking and platforming dexterity, but also because you're never used to killing yourself. Most games people ever play involve avoiding death, so much that this reversal is an interesting mechanic all by itself.