My current pet idea is Dereliction.
Singularity came and went. It went badly. The Solar Federation is in ruins. Its once-proud ships and stations are derelicts haunted by technological and biological horrors. Its colonies are death trap tombs. Only Terra remans - clawing its way back to space out of desolation. The new Terran Union needs the technological artifacts of the past to help build its nascent industrial base. Such artifacts abound in pre-Signularity derelicts. As the small Terran Navy has its hands full, the Terran Union outsources this dangerous exploration to (fool)hardy individuals, typically ex-military. You are such an individual. A licensed Stalker. You go to dead star systems to salvage machinery from dead ships, confronting their dead crews and robotics. The government pays you in cash for every artifact you bring back. You may even keep useful items you salvage from ships - the government needs machines much more than it needs individual laser rifles. Keep us the good work, stay alive for long enough - and you might even get a highly coveted Colonial License to set up your own extrasolar colony. Vast fortunes await - or an early death. Most likely, an early death.
My initial thought was to do this using Sword & Wizardry: White Box rules, which are simple and easy to work with. But this may transition into ACKS rules, which are much better but also much more complex to work with.