The large box in the back of the screen is more indicative of what colour is currently active. By keeping track of it using the wheel and observing the lanes at the same time is rather difficult to keep focus...
Have you tried the updated version already?
With the additional visual feedback it emphasizes the front facing side of the blocks while they are vulnerable.
If you think it difficult to find out how to play because it lacks feedback on players' actions then it's the game that needs to be improved. But then, having games that need polishing in their game-play because they lacked play-testing is certainly part of game jams...