There are keyboard controls. You might first need to click the game area to get keyboard into focus.
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I though it might be something like that and tried that. I also clicked the window multiple times when playing with the mouse, but then when trying to use keyboard, it did not seem to do anything... Well maybe I have to test again. There have been some issues with my keyboard lately so that could be the reason if the game works properly for everyone else.
EDIT: Yeah, I tried again, and this time it worked with no problems. Guess the problem was on my end. Being able to use the keyboard definitely made it more fun to play.