Not bad.
The anti-cheat system is beatable: I was able to right-click at the menu where you select how many dots you want, then left click and hold on one of the buttons (such as "3 Dots"). I then move the mouse off-screen and release. So there's some improvement to be made there.
In multiplayer, the keyboard player should be able to hold a key to make the dot move, and the dot shouldn't be able to move off-screen (that's what I think anyhow). I understand this is a learning game, but these are the things to work on.
When I played single player, the first option I chose was endless and 15 dots, and it turned out to be fairly easy, mostly because of the movement of the dots. They kept on moving in circles, which made them fairly easy to dodge. I think I know why you decided to do this, but you might make them move in these circles, while at the same time they move around the screen at a bit of a faster speed.
Challenge mode was interesting, I think you did a good job on it.
Other than that the game does exactly what it should, and I haven't had any strange menu button issues like some others seem to have.