Unfortunately, I didn't understand at the beginning how to place a dice. I did it by positioning the mouse in a cell, pressing the left mouse button and then dragging down. I don't know exactly if that's the correct way. Maybe considering to add a control tutorial to your game page? The enemies also get very fast over time, which makes it impossible for me to place a dice in time. I also had trouble launching the game in Chrome. I then switched to Firefox.
What I like about this game is the strategic placement of dices. Because if two adjacent dices have the same number, they disappear, which gives you more space, to place more dices.
Overall i think this is a good submission.