I might do something like, two or three of the player characters are software engineers and they've been slaving away on their free time to revolutionize the way computers analyze data. They suffer through a couple of days of their crappy day jobs, only to get together at night. They are each others sanctuary from the banality of their lives and their project is the promise of a better life, a light at the end of their tunnels. Then it happens, the big call, the megacorporation has seen their prototype and wants to talk. A conference meeting later and it's done, they've signed a deal to sell their software to Cyberdine. After years of slaving away in obscurity they're going to be rich, like seven figures rich. Let them taste being able to quit their crappy day jobs, tell their abusive bosses to shove it, buy expensive cars, blow money on girls at night clubs. Little do they know their software is the basis for what gives Skynet the ability to learn and become self aware. Humans from the future have been sent back by John Conner to murder the player characters and a terminator has been sent back to keep them alive until the software changes hands. Then turn it on the player's heads when they find out the truth. But now it's too late the software is already in the "wrong hands." The players must break into a secured facility to steal back their own creation, only the terminator isn't keeping them alive anymore, it's trying to remove them as a threat. The player's only allies are the humans who were just trying to kill them hours before. For funsies maybe have one of the players be a human from the future, if that's not too hard to work into the concept or keeps them too excluded. Or! Maybe the character is a re-purposed terminator from the future working for the humans.
