Well, the issue becomes "what''s the tech for?"
Usually, it''s just for fighting. So in an CRPG(-like?) like Fallout, the system is varying guns. Range, rate of fire, accuracy, weight / kick, and ammo and damage type (armor piercing, hollowpoint, etc) become issues for the system to deal with. There are countless varieties on this, just as there are countless swords, and what you use depends on situation. And this isn''t even touching futuristic ("phased plasma rifle, in 40-watt range"

)
Other systems depend on how much you''re willing to invest in a certain type of gameplay. You could have issues of varying drugs and treatments vs. bacteria and virii if you flesh out medicine.
You could have systems that deal with gathering information (spy cameras, infrared equipment, disguised devices) if you flesh out spying.
There are lots and lots of choices. In fact, the comparitive complexity level of modern or futuristic times gives you, depending on your perspective, a boon or bane of possibilities.
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Just waiting for the mothership...