Press "P" to pause the game. While paused, hold the left mouse button and press "F1". The border will briefly flash and your spaceship will build an impenetrable shield. Then press "P" again to return to the game!



Freezer:

01497F = Lives


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Source: Amiga Future GTT

Additional Freezer Addresses:
0149F3 = Credits
1497E or 105E = Lives (alternative, set to 0 or TST $4A)
14954 or 333E = Collision (set to 0 or TST $4A)
14955 = Invincibility (TFD 14954, set value 10 before executing TFD)