Achilles

The first game has been reduced to abandonware, so it is available here. You'll most likely need DOSBox to run it, though. The first thing that you'll notice about SS1 is a certain "Citadel Station".

SS2, on the other hand, is ridiculously hard to find, and is selling for astronomical prices on eBay and Amazon. As much as I hate to resort to it when it comes to products of such calibre as with SS2, I'm afraid that you'll have to "get" SS2.