So, what exactly was the Darksider franchise's problem? Anyone say marketing?

[DaRev]

I'm not sure but it could be because people often relate or compare a new franchise like Darksiders or Castlevania LoS to existing, and highly favoured franchises like Zelda and God of War. Gamers, IMO, often make such comparisons to the detriment of the new franchise. Maybe that's why games like Darksiders (good game), Dante's Inferno (not so good game), or even PSASBR will always be compared to other well loved franchises and therefore overlooked and not sell well.

So, gamers are the problem