This is a liberated game: it was originally shareware, but Screaming Duck Software generously released the full version as freeware (please see the links section below for the download).
Shooter, 1994Freeware, Source code
Shooter, 1994Shareware
Shooter, 1997Shareware (installed), Shareware
Shooter, 1999Freeware (installed), Freeware
Shooter, 2004Freeware (installed), Freeware, Source code
Shooter, 1996Shareware
Shooter, 1986Freeware (installed), Freeware, Source code
Shooter, 1996Full version
Shooter, 1999Playable demo (installed), Full version, Extra