Is this for the PC or PPC? It is supposed to run in fullscreen on the PPC because of coding in PocketHAL/FROG. It doesn't support anything else.
However, PPL uses:
InitGameAPIEx(h$, &GameProc, 240, 320, true, 20, 0);
the fifth parameter is for fullscreen. However, it shouldn't matter on the PC. It won't go fullscreen. You can, however, set the resolution to other resolutions and it will work.