'Master Prospector' is an achievement on Steam. Once the final boss is defeated, your performance is rated on four parameters: time, total amount of gold received, number of orbs collected and number of deaths. Each of your results is ranked as either bronze, silver or gold and the achievement requires 4 gold stars. There is a part of mystery, as the thresholds for each star are not specified anywhere in the game; but I'm sure of one thing: you must avoid dying to get the corresponding gold star.
There are 54 views in 23 videos for SteamWorld Dig. The game makes up 6 hours of published video on his channel, or 2.92% of the total watchable video for SteamWorld Dig on Rinstor's YouTube channel.