On-Line Systems was founded in 1979 by husband and wife Ken and Roberta Williams. It was renamed Sierra On-Line in 1982. 

Games by On-Line Systems:
1982

Graphical Text Adventure. An adventure game aimed at children. Free 16 animals captured by a dragon.

Graphical Text Adventure. Travel through time, solve puzzles, and meet historical figures.

1981

Graphical Text Adventure. Enter Cranston Manor to find the 16 treasures to break the curse of the town of Coarsegold.

Text Adventure. The text adventure that was the basis for Leisure Suit Larry.  Find items to win the affection of various women.

Graphical Text Adventure. In ancient Greece, Ulysses must retrieve the golden fleece, a treasure protected by the gods.

1980

Graphical Text Adventure. An astronaut must travel to an asteroid, and blow it up before it collides with the Earth.

Graphical Text Adventure. Search for treasure and uncover a murderer or else become the next victim.

Graphical Text Adventure. A wanderer in the kingdom of Serenia must rescue the king's daughter from an evil wizard.