Credited names: Sierra, Sierra Entertainment, Sierra Studios

Oldest to newest, including sub-studios. Releases with unknown years appear last.

1. 1998

   • Half-Life

     Sierra (publisher)

2. 1999

   • Half-Life: Opposing Force

     Sierra Entertainment (publisher)

3. 2001

   • Half-Life: Blue Shift

     Sierra Studios (publisher)

   • Half-Life: Decay

     Sierra Entertainment (publisher)