I treed to understand what's going on in the game twice. Yesterday just after submission there were opponents and today – there was no one, but i launched second session in other browser window.
All i was able to figure out is that ball falling at right part of the screen can be handled by a/d/arrows and that it explodes contacting ball of opposite color.
Sometimes green dots appears. Sometimes white disc around the ball. Often it seems indicating other balls in range but in some cases it was just white disc without other balls.
Possibly the impression could be better due to detailed description of the mechanics, the goal and controls. The worse the session is too short. Start - something happens - guest XXX wins.
Its even hard to say who is the winner – you or other player. I didn’t understand also is there any interaction between users, or you just can see his/hers gamefield (which increases complication and obscurity of action on the screen). As long as something happens even without actions of any side, single player mode could aid learning the mechanic.
As for a good moments. There definitely are some action gameplay which could be fun if your understand what's going on, the visuals is very solid and i appreciate the challenge of developing a multiplayer game.