A pioneer in the adventure gaming genre. Inspired by William Crowther's trips exploring Mammoth Cave National Park in Kentucky (which is the largest cave system in the world), the game uses a text parser to control actions. It was ported to DOS by Microsoft and was the first game commercially available for the IBM PC at launch. As a result, it's one of the most important games in history.

It's also pretty decent to play. The puzzles are decent, and the text is well written enough. The problem is the key parse is very picky on what words it accepts. I died countless times trying to kill the Dwarfs before they killed me simply because I couldn't figure out how to use the axe in my inventory. Infocom would release Zork in 1980 and improve the parser, making these kinds of games far more playable. Its a little archaic, but the fundamentals are there and would go on to inspire many other games.