Aliens threaten to destroy the earth via a huge bomb embedded deep within the planet. As a challenge to the human race, they have agreed to let Earth's finest pilot to get into a high-speed ship to get to the bomb before the timer runs out.
Your ship has minimal shields to protect you from slamming into walls as you navigate the deep underground tunnels. But it's not easy: You'll have no idea which tunnels are the fastest/shortest until a split second before you get to them, and there are alien weapons trying to destroy you along the way.
If you manage to complete the run and save the earth, you can tell the program to randomly generate an entirely new game with different tunnels for endless replayability.
The animation technique used for Tunnels of Armageddon displayed a rushing sense of speed down tunnels. Because it was a fairly simple display technique, the game was playable on low-speed machines, including the original 4.77MHz PC and other slow machines like the Apple IIGS.