The Diablo series is perhaps one of the most underrated series all-time. Diablo 2 came out in 1999 and still has a following on Blizzard to this day. I cannot think of a video game that has a following for that long (perhaps WoW). I don't think it gets a lot of attention due to the units sold argument. However, I heard something crazy the other day that kind of destroys the unit solds argument.
I am a huge strategy game fan and I follow someone called Melkor on Youtube who does videos on the Total War series. SEGA is pushing the Total War series and Creative Assembly to make a move towards what they call Super Games which is a comparison to Paradox.
So to compare two titles: Rome Total War 2 sold significantly more games the Europa Universalis 4 for PC. I mean it is nearly double the unit sold. However, EU4 rain a string of DLC and has kept the game alive to date. Its online userbase on Steam has actually increased since its launch almost 8 years ago. As a result, Paradox has made four times the $$$ of EU4 than off of RTW 2. Kind of a crazy though that RTW2 just destroyed Paradox on units sold but Paradox is making more money per title due to the constant DLC and updating of a game.
I see Diablo 2 as that way. Although it probably has less unit sold than many games, it is perhaps one of the most followed and played games in gaming history.
Diablo 3 is meh though
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. Sounds like the two of us play a lot of the same games.