Over a lazy weekend I stumbled on Starship Troopers II: Hero of the Federation (2004) and Starship Troopers III: Marauder (2008). Neither were very good, but they weren't terrible either. Both were straight-to-video offerings made at about one-tenth the cost of the original Starship Troopers (1997).
What I found interesting, however, is how the movies were marketed. You see, the second one isn't really a sequel. The characters and actors are different, and even the genre is not the same as the first and third movies. The second one is sci-fi/horror, rather than sci-fi/action adventure as are the first and third. The only similarity to the original is that it's set in the same futuristic world where humans are fighting the same war against giant alien bugs.
An analogy: a movie studio makes a fictional World War II movie, then makes another fictional World War II movie. Is the second one really a sequel to the first?
Troopers II has been criticized chiefly because it wasn't like the original. III had a better reception because it was closer to the original in spirit, had a character from the original, and even ratcheted the satirical themes of the first one up a notch.
But while I'm not "recommending" either film, I'm a fan of the idea of creating characters and storylines within fictional worlds that were originally created for other characters and plots, which II accomplished. And to have that world cross genres.
For example, how about an Edwardian comedy of manners, in which Sherlock Holmes is mentioned as a real person, but never appears?
Or a legal thriller about deceit and fraud in the insurance industry from damage wrought by a battle between, say, Spiderman and a supervillian?
How about a present-day archaeology adventure about a mysterious object discovered in the mid-20th century by "Henry Jones, an eccentric professor who liked to call himself Indiana."
Why not adapt screenplays set in spaceships of the future to be in the "universe" of Alien or Star Trek, even if Ripley or Captain Kirk aren't around?
The movies have created so many worlds already. I would love to see more movies set in those worlds, even if they don't include the same characters.