From the menu if you hit fire button the game will start.
You don't "MUST" to give a pass-code. If you do not have one the game will start at the last available/played level (level 1 by default).
About the "blank screen":
It usually comes when you (in case of OS3.2) start the game with the "ProjectHorizon" executable and not with the "ProjectHorizonOS32" executable.
It is becose for some reason (completely beyond our control) OS3.2+KickRom produces a continuous input button signal as if a CD32 controllers third (yellow) button was triggered continuously. The blank screen comes when the game (level) starts and at the same moment tries to show/hide the map (that is what the third button do), but it can't becouse the button leading it to an endless cycle.
The support for CD32 controller was a feature asked by the community. There is no possible way to detect if there is such a controller present or not (to solve the issue inside the game).
The solution should be: As i described before, please start the game with the "ProjectHorizonOS32" executable. And (in case the game has its own partition) modify the starup sequence if necessery .
No other modification is necessery!