Each field can only take a limited number of counters; if you add more, it is overloaded and explodes, shattering fragments to the left, right, top and bottom of the exploding field. These new fields all will have your colour and one more counter than before. This graphic illustrates the maximum number of counters per field
If this causes another overloaded field, that one will explode and so on. The game is finished when all fields are of the same colour or empty.
It's also possible to activate a countdown timer, which limits the thinking time for a move. If you are too slow, you lose the right to place a counter in this round.
To the left and right of the central board, player information is displayed. This includes a preview of the appearance of the counters for a load of 1-4. Typically, the counters represent load by increasingly bright colours, so it's good to have a reference.
At the bottom, you see four buttons. Their functions are, from left to right: