In GURPS you need to do a lot more front loading, especially when using a home brew world. with all the options available the key is to start with your limitations on the world. what won't you allow. no magic, no time travel, that sort of thing. then move on to specific limitations that fall within your specified genre. cybernetics are allowed, but gene modification isn't, or the other way around. then you need to look into what skills are going to be used all the time, then you want to either raise the point value on them(to encourage focus), or lower it(to encourage diversity). also what advantages are allowed, what are disallowed, you need a list of those before character creation. on the plus side once you have done all that work, the game runs fairly smoothly. with GURPS, however, the more work you do upfront, the better the game will end up.