Really fun game idea, gives me big Agar.io vibes!
Two things I noticed: (1) expanding to full screen showed more of the game world, rather than just making the existing viewport larger, this made playing the game a lot easier and I can imagine people playing without fullscreen feeling a bit lost due to the size of the map/how many numbers there are to find! (2) That movement speed is tied to how far the mouse is from Bob. This meant that I could hit around Mach 4 speeds by cranking my mouse to the opposite diagonal side of the screen when in fullscreen mode - possibly a bug, but actually made for really fun play!