Search was: year = 1979
Adventure International: 0: Adventureland Demo (1979)
Adventure International: 2: Pirate Adventure (aka Pirate's Cove) (1978-1979?)
Adventure International: 3: Mission Impossible / Impossible Mission / Secret Mission (1979)
Mad Hatter Software: Sorcerer's Castle (1979)
Mad Hatter Software: King Tut's Tomb (1979)
Mainframe adventures: Zork (aka Dungeon) (1977-1979)
Mainframe adventures: Brand X (later Philosopher's Quest) (1979)
Mainframe adventures: HAUNT (1979)
Mainframe adventures: New Adventure (1979 or 1980)
Mainframe adventures: Martian Adventure (1979 or 1980)
Mainframe adventures: Battlestar (1979)
Personal Software: Zork (1979)
Sierra On-Line, Inc: 1: Mystery House (1980 (written during 1979; rereleased by SierraVenture 1982))
Softside: Dog Star Adventure (1979)
Softwin Associates: Microsoft Adventure (1979)
Various companies: Darth Vader Adventure (1978-1979 or earlier)
16 games match your query.
Adventureland was created by Hans Persson and is now maintained by Stefan Meier.
If you find any errors or have information that is missing, please let me know.