When running (default RIGHT MOUSE BUTTON) you are burning your stamina. You will regain it when trotting and even faster if you stand still.
When passing the ball (default LEFT MOUSE BUTTON) your player will keep its bearing so you can kick the ball in any direction without turning. The longer you hold the button the stronger the kick.
Use slide (default SPACEBAR) to stun your opponents and capture the ball. You will slide further if you are running.
Thrown on the playfield by an angry hooligan. Use it to stun your enemies (default SPACEBAR). Note that you are moving slightly slower when holding a chair.
Shout (default E) if you want a team mate to pass the ball to you.
If you are feeling lost the white circle shows where the ball is while the red arrow points at the enemy gate.