I know. It's somewhat like a Half-Life 3.
If you're interested go for the 4 "Origins" volumes. The limited edition I've got was on sale for cheap (estimate ~2.05$, different currency here) and also included the first two volumes, among other things. The rest I've got through some other, unconventional means.
No idea about the others, but these are pretty much what is needed as "extra backstory material". All the remaining Darkness comics seem to range some other way. They'll probably either make you love the story more or consider it cheap (taken apart on a basic overview, that is).
Quite a while ago I've completed my second playthrough of
The Darkness II and 100'ed everything. Needless to say, only now did I realize how short the game was. There was this one relic right as you enter the final level which spoils everything moments away from happening.
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Along with this I've also tried
MINERVA: Metastasis (Half-Life 2: Episode One mod). Took me about 3 hours to complete (hardest difficulty), which is moderate length for mods. It was amazing though. The Stalkers can be interacted to a bigger extent than what was shown in the original game.
Spoiler
There is this one skybox in the game with a red-tinted clouds at the top, signaling the Combine superportal opened by the Citadel. In the mod though it is used to signal an orbital strike. Clever use of skyboxes, what can I say?
Now I've just started
Deus Ex: Human Revolution. The interface seems a bit more confusing/lacking than the first, but I hope I will get used to that. Story wise it has not proven amazing but manages to keep my attention. The combat is much more improved although it is obvious it's not one of the main aspects of the game.