Congrats on submitting your first game, this is a really great starting off point. Unfortunately I'm playing on a laptop without a number pad so I can't change colors. I know someone else mentioned the screen size, but depending on your game engine, you can change how the game scales with screen size. For example in Godot, you can change the display/window/stretch/mode to "viewport". A quick google should assist if you're in a different game engine. Anyway, nice work!