>>47638893It was myriad of things that killed it
The card and add-on system was too complicated and added needless complex to a game that should be a simple bro-op shooter (plus it incentive you to buy DLC for better stuff)
Got ruthlessly shitted on because it wasn't L4D3 or L4D2.5
Had a really shakey release with lots of bugs that took months of patches to iron out
