Hi and thank you! Code 103 means not enough memory.
Roguecraft needs at least 1MB Chip RAM, which you should have with the ACA500 if you have a Rev5 or above motherboard (ECS Agnus).
If you have multiple hard disks, then the drivers for them eat quite a bit of memory, so you could try disabling at least one of the hard disks at boot, and the game should run from ADF too on the A500. 😊