Manic Miner is the first game in the Miner Willy series. It is well known for being one of the most influential games in the platform genre, being the first game on the ZX Spectrum to feature in-game music (although it's disabled in this TAS to make the game run faster). The story goes that Miner Willy falls down an abandoned mineshaft and has to navigate through many rooms while collecting treasure and making his way back home.
DigitalDuck & crem run through the mine and help Willy get back so he doesn't miss his favorite TV show.
Gameplay starts at 3:15