Display of game variables on screen

[worldpeace-germany]

Hi,

I am able to display player variables on the screen, e.g. (ball) as well as machine variable, e.g. (machine|mpf_version). I am failing on displaying game variables.

This fails:
(balls_per_game)
(game|balls_per_game)

where fails means it just shows the text inside the ().

Have I missed something in the documentation?

Thanks!