You realise most of the so called "sequels" weren't actually licensed as sequels at all, they were completely different games, by different companies/people as more of a homage to the genre.
The lead designer of the game never really did much (of note) beyond that game. In fact he mostly just kept making that same game over and over again, tried forming his own game company, twice, failed both times. Here's a game he did for the game-boy advance:
Rebelstar: Tactical Command Review - GameSpot.com