Shareware is a software marketing concept where an incomplete or time-limited version of a program is released to entice people into buying the full (registered) version. Doom and Heretic were both initially released as shareware, each containing only the first respective nine-level episode in the unregistered version: Doom: Knee-Deep in the Dead and Heretic: City of the Damned.
Part of the reason Doom II was not given a shareware release, according to John Carmack, was that "[a] lot of people consider themselves to have "finished DOOM" when they just finished the shareware episode."
- Doomworld.com (1999), Interview with John Carmack, (question 15). Retrieved on April 11, 2008.
2. Not important, but using the idfa or idkfa cheat on the shareware version still does not allow use of the Plasma Rifle or BFG9000
- Doom: Knee-Deep in the Dead v1.9 (and text file), at the id Software FTP site.
- Heretic: City of the Damned v1.2 (and text file), at the id Software FTP site.
- Download Hexen 4-level demo
- Download Strife teaser v1.1
- Shareware Wikipedia article