Some players reported have problem to use ARROW keys ( ) and running (SPACE) at the same time. Investigations were made but nothing found.
The problem doesn't come from the game or the browser but from your keyboard controler. The controler of the keyboard handles the simultaneous pressing of several keys. All controllers do not manage in the same way.
For example, i bought a new keyboard last week (mecanical keyboard, the top! ). With the previous one, i have this trouble to turn well. With the new one, no problem.
@berenice reports that her SHIFT keys don't work for laying , on her 2 computers. Very weird problem because 2 SHIFT keys per computer = 4 SHIFT keys not working?!