Tug Bug

You almost suspected it: The Tug Bug is a device from a computer game which Alex Fredebeul and Peter Kienle set out to create in the late 80s.
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Because Peter relocated to the US in 1988 the game never got finished but the Tug Bug is popping up every once in a while. Here's the earliest incarnation:
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Recently the Tug Bug has been seen together with Marvin, the Robot lugging acme records CDs around.
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Rumors have it that the original source code of the game has been found and is now being implemented for the Macintosh.