In my college days, I ran a Sci Fi rpg and had people from all walks playing. What I did was spend time with the players helping them create a character.
I would have them bring stories, pictures (Epic, Heavy Metal, Comic books, graphic novels) or movie ideas with them. I would even have a stack of various Sci Fi type material handy. Then the basic questions I would ask:
What do you want to do in the future?
What kind of items/gadget/vehicles do you want?
Then we would go from there. I would not grant everything that they wanted but explained that it was a big universe and I would make sure that they had some clues/direction to get where they wanted.
Some times an entire adventure would start from someone deciding they wanted something. I remember once a female who was not much into role playing decided that she wanted a pet (she just lost her cat of after 9 years). The group started asking her what kind she wanted. She did not know, so they all went window/catalog shopping (pulled out all the Epic's, Heavy Metals and movie reference we had laying around). She found an alien that looked interesting. So off on to an adventure that took 5 weeks of gaming to accomplish (about 6 hours a week).
The point behind this is everyone has dreams/imagination. We should not get bogged down on the dice rolls, charts and rules. We should instead take someone's dream/idea and run with it. Now, it make take some planning ahead to make the adventure worth while but if you know the rules/system and you know your players, you should be able to keep them challenged with out much work.
Look at various TV shows and movies. Star Trek had transporters and in the beginning no one cared how they worked. As time went on some did, so then they had to make up more details about it.
Many movies that we enjoy, we do not worry about all the details of how something works but that it works to make the story interesting/move forward/become a goal.
In my game when someone wanted to learn/create/tear apart something we made that the side adventure for that character. Of course they could set that character aside for a time (usually min of 8 weeks 'real world' with out playing it) to learn the new something. I find that most players are not willing to part with their character that long to get that knowledge/skill so they suffer/work on it during the adventure(s) while still traveling with the group. Then it takes them 4 months 'real world time' or so to learn the something and it was more fun because of all the opportunities it created in the adventure.
(Most stop writing so much in one sitting.
Dave