Marble Madness
Extra time - Stomping the Baby Baddies in the nursery on
the silly level gets you an extra 3 seconds for each one.
Playing the game in 2-player mode (even if the 2nd player
never rolls) gives you extra credits/time for winning
each race.
Extra time cheat - Hold either start button down while flipping
the test switch (on the ARIII board). The first flip bumps
you up to 99 seconds left, from whatever you had. Successive
flips each add another 99 seconds (but wont display
on the screen as it will only show 99 max.)