The 1-player EM version of this game is INDER's 1977 'Shamrock'.
INDER implemented helpful ideas for maintainance, yet reportedly this machine was very unpopular with operators. These ideas included:
� A single playfield stanchion is centered, thus no danger of a raised playfield tilting.
� A switch is mounted inside the cabinet allowing the repairman to interrupt the current while turning on a common light bulb for small servicing jobs.
� The transformer allows switching between all known voltages with just one jumper.
� The relay board can be easily removed after removing the plugs, including unplugging the main current supply line.