Overview of the Series StarFight I, II StarFight III:
Within the Darkness
StarFight IV:
StarFight V:
Hell's Gate
StarFight VI:

Overview of the Series
StarFight game series is the industry's longest-running series of freeware or public-domain scifi adventure/action games. Total of six StarFight games have been developed since 1996, and the seventh one is on the way. No other non-commercial game series even comes close to this.
Since each StarFight game is very different from the other, one could wonder whether a defining idea behind the games exists. Is there a direction in the games, and if there is, towards what kind of gaming is it taking us?
Story Matters
StarFight games are all about the story, it is what in the end connects them. The entire purpose of any StarFight game is to deliver it's story using whatever means chosen for that particular game. Combination of genres and cinematic sequences have been chosen as the means of delivery by StarFight games in the past.
The Action Aspect
The only genre that has been somewhat present in every singe StarFight game has been space shoot-em-up action. The style of the action varies from short, simple vertical scroller type action of the StarFight IV's action sequences to full-blown, semi-tactical open universe capital ship combat of StarFight VI. The action aspect of the StarFight series is not to disappear in the future, nor will it be less emphasized.
The Adventure Aspect
StarFight episodes I, III, IV and VI have had distinct adventure sections in them. Adventure sections assist storytelling the way action can't. In StarFight IV, adventure sections deliver a humoristic survival story on a ship whose computer's gone mad. In StarFight games III and VI, adventure sections are used to establish the charachter of the hero, his crew and his adversaries.
Distinct adventure sections are something that will disappear from StarFight games in the future. Adventure elements of gameplay will not go away, however...
Ultimate Goal: the Seamless Combination of the Two
With the seventh episode, StarFight: Comrades, the ambitious goal is to produce  action, adventure and role playing games as one seamless entity. StarFight VI: Gatekeepers was a step in this direction, but just rather a small and careful one.
There hasn't been a game quite the next StarFight title since Star Control 2, and the reason is obvious: challenge of developing one is enormous. A story has to be integrated with a single, continuous and free-form game world. And being able to create that combination is not enough; the creation has to have good performance, proper balancing, and most important of all, enjoyable gameplay experience.
For better or worse, StarFight: Comrades is going to be something unique.