An awesome game plagued by a weak retail box and very expensive expansions. I have all the content released so far (minus boosters with one miniature) and the game is massive: - 20+ scenarios, plus the cards to create your own. - 70+ enemies. - 90+ equipment to gear up. - 28 playable characters. However, with the money you pay for it all you could buy, let's say, Mage Knight UE, Nemesis, Tainted Grail (base game) AND Cthulhu DmD (base game).
The base game and each expansion is meant to tell one of the specific story arc from the Hellboy comics, that's why each feels "samey." But I can understand if you're looking for a game with tons of replayability and variety. The BPRD Archives expansion lets you create one off scenarios, and with a couple of the expansions it lets you combine different monsters. Lastly, I agree that there is a lot of fiddling around and things to remember, and the tracking of the scenario cards, but I try not to let that ruin the overall experience of playing as Hellboy and punching and shooting monsters.
I think a full campaign with all of the 20+ cases wouldn't fit, even because some case files are very distant in time in the Hellboy lore, but it should have a mini campaign for each box of content.
