IAmSinistar: Stronghold Collection is $4.99 (75% off) at GG. It includes Stronghold, Stronghold 2, Stronghold Crusader, Stronghold Crusader Extreme, and Stronghold Legends. It has "Other DRM", which is a pretty unhelpful descriptor, so if anyone knows what that might be in this case, please post.
I bought that collection last year. It required online activation and used one key for all games included. I had to register the key only once, the other games recognized that the product was already registered.
I _think_ it was just a regular SecuRom key, but I may be misremembering it. It wouldn't be the first time that a DRM description is less specific than it could be; on the other hand, it woldn't be the first time that I'm misremembering something either. ;)
nightrunner227: I recommend Doorways. There will be 4 chapters total, all available at Desura as well. It's not the greatest thing in the world, but it does get spooky. Also, it includes scenes of torture and has Alexander from Amnesia TDD narrating.
I haven't seen much information about Doorways, but you're actually the first person I see who bought the product and seems happy with it ... whatever that means. ;)