Seems Gargoyle Games began their advertising campaign for The Siege of Earth trilogy with release dates.
As the other two games were never released, I don't know if these dates can be trusted. But anyway, we can:
Add the release date for Marsport - September 1985
Add the release date for Fornax - January 1986
Add the release date for Gath - April 1986
Improve or remove comments related to the trilogy.