The Myth dump has been patched to remove the protection when running on a C64.

The LDA $F72C instruction at $C9 in the dump file (at address $80C9 when
loaded) has been changed to:

JMP $80E6

Without this, you must type the following on the blank screen (including
spaces) to start the game on a C64 (on a C64GS it autostarts without this):

SYS 3 MYTH