Core Mechanic: The gameplay was scary, but in a fun way. Accidentally offing myself in the starting chamber was a nice introduction for what was to come, as was the robot voice and general aesthetic. The slow escalation in chaos and fear was a strong element as well.
Game Feel: The movement was smooth and fluid (aside from the platforming section at the end), shooting felt nice, and dying was jarring and painful.
Visuals: The visuals being reminiscent of Portal made it very easy to understand what the game was all about. The grayscale environment with dark, shadowy lighting and skybox were ominous. The glowy colorful targets and b alls made them stand out from the rest of the environment and also from each other.
Sound: Never has a xylophone hit been so terrifying; hiding in the bunker in the last puzzle was harrowing like a war movie.
Theme: The chain reactions were a cool aspect, but it didn't happen super consistently. Several times I would lob a shot at a yellow ball and it didn't even destroy any others in the room.