Classic old school DOS game from 1983. Levels get really hard later in the game.
Source:

Loving would be easy if your colours were like my dreams,
Red, Gold and Green,
Red, Gold and Green.
Karma Chameleon, Culture Club, 1983.
Introduction
Digger was originally created by Windmill software in 1983 and released as a copy-protected, bootable 5.25″ floppy disk for the IBM PC. As it requires a genuine CGA card, it didn’t work on modern PCs.
In 1998, I created Digger Remastered, which runs on all PCs with CGA or better and plays just like the original. It also has many new features, including:
Exit button
Optional VGA graphics
Recording and playback
Real time speed control
Keyboard redefinition
Gauntlet mode
Two player simultaneous mode
Highlights
Welcome to the official website of Digger Remastered. Here you will find everything Digger-related you could possibly want. While you are here you can:
Download Digger and related files.
Play Java Digger.
Read the original instructions.
Find out what’s new in the world of Digger.
Discover who are the champion Digger players in the hall of fame.
Join one of the Digger mailing lists.
Discover everything we know about Windmill software.
Become part of the latest craze to be sweeping the world. I’ve had thousands of emails from people all over the world thanking me for making Digger available again.
Included with each version of the game is a text file which contains some of the information from this site.
Help wanted
As is abundantly clear from the tumbleweeds on the What’s New page, I don’t have much spare time to work on Digger at the moment. The Digger community desparately needs someone new to take over the project, update the website and do some much needed development on the game itself.
Are you that person?
This site was The 80s Server’s “Totally Awesome site of the day” on January 25th, 1999.
Q: How does the scoring system work?
A: As follows:
Emerald (): 25 points.
Eight consecutive emeralds (octave): Extra 250 points.
Gold (): 500 points.
Killing a Nobbin (Nobbin) or a Hobbin (Hobbin) by shooting (Fireball) or hitting with a bag (Bag): 250 points.
Bonus (): 1,000 points.
(In bonus mode) Eating a Nobbin (Nobbin) or a Hobbin (Hobbin): 200 points for first, 400 for 2nd, etc. (doubling each time) – still 250 for other methods of killing, though.
At every multiple of 20,000 points you get an extra life.
Q: What’s the most you can score?
A: The maximum possible score on completion of level 1 is 8,650 plus 3,900 for every life used. I can repeatably obtain 8,650. The maximum possible score you can have by the end of level 2 is 19,925 if you don’t die, so it is not possible to start level 3 with more than 2 lives in reserve. I have got maximum score on the first two levels a few times.
I haven’t bothered to calculate similar statistics for the other levels, but I can if anyone’s interested…
If you meant “What’s the most you’ve ever scored”, the answer is 75,975. [91,675 for VfB]