Hey, great job for your first game!
One thing I found a little strange is only my numpad worked to change colors which I found a little strange, but that should be an easy fix.
The sound track is a little repetitive, and if you are doing a game where color matters a lot, try to avoid colors like red and green to make it more accessible to people who are color blind, especially for stroop difficulty.
Otherwise, its a really cute game. A simple idea and well executed. Nice Job!