Workbench: Double click on the onEscapee icon named "Start".

CLI: Change directory to onEscapee: ( eg: 'CD onEscapee:' )
then execute the "Start" file ( eg: 'execute Start' )

VGA monitor users: Run the program EscMode to choose the right screenmodes.
You have to choose 2 screenmodes, one for the game screen (320x256)
and one for the menu screen(640x400).
Or you can use screenmode promotors like 'NewMode' as well.

The game uses Locale settings to get the preferred language.