GPL licensed (37)

Alex the Allegator

Also known as Alex the Allegator 1

Platform, 1999
Freeware (installed), Freeware, Source code

AllegroHack

Role-Playing, 2000
Freeware, System component

Barren Planet

Turn-Based Strategy, 2023
Freeware (installed), Freeware, Game expansion, Extra, Extra

Buzz Aldrin's Race into Space

Simulation, 1993
Non-playable demo

Catacomb

Also known as Catacombs

Shooter, 1990
Freeware

The Catacomb Abyss

Also known as Catacomb Abyss 3D

First-Person Shooter, 1992
Shareware

Cylindrix

First-Person Shooter, 1996
Playable demo (installed), Full version, Source code

Digger Remastered

Arcade, 1999
Freeware, Freeware, Freeware, Extra, Source code

DOOM

Also known as Doom: Evil Unleashed

First-Person Shooter, 1993
Shareware (installed), Shareware, Shareware

DOOM II

Also known as DOOM II: Hell on Earth

First-Person Shooter, 1994

Emeritus Pong

Arcade, 2008
Freeware (installed), Freeware, Source code, System component, Freeware

Gladiator

Role-Playing, 1995
Shareware, Source code

Heretic

First-Person Shooter, 1994
Shareware (installed), Shareware

Heroes

Arcade, 1998
Freeware

Hexen II

Role-Playing, 1997
Playable demo (installed), System component, Playable demo

Hexen: Beyond Heretic

Also known as Heretic 2

Adventure, 1995
Playable demo, Preview, FAQ