I worked on Marble Madness Master System as a Producer for Virgin Games.
The project was built by Steve Lamb who was based in the south of the UK. He was a great guy to work with and I used to travel down to see him from time to time to check on progress. At the time this was being built we’d just got 14,400 baud modems so Steve used to send eprom images up via the phone and we’d burn the ROMs in London to allow testing.
Full Playthrough can be found here
Thanks to Moby Games for screenshots