For me it's Diablo II. Granted I've played my fair share of D2 since launch, and also recently on a private server with a comrade from hexbear, but I still feel like years later the game didn't grab me as much as D1 did.
Granted I don't hate D2, but for a game that I keep coming back to, D1 takes the prize.
I don't play Total War, but I do play tabletop. Cold Ones have "stupidity," which means the player can lose control of them and they'll perform a random movement. It's really, really, really bad when your Cold One Knights decide they're going to go look for food off in the corner instead of charging that group of Chaos Warriors.
They also have one of the worst movement speeds of any heavy cavalry in the game at only 7 inches, especially with their cost. They do more damage than horses and have more attacks than boars, which is nice. But between Orc WAAAGH! powers giving boars more movement and horses just being faster, that may not matter if they charge you first.
Still, they're the heavy cavalry unit for both Lizardmen and Dark Elves, so people take them regardless. Especially in 6th. Edition where cavalry was a little too good. You still wanted heavy cavalry units to break through your opponent's infantry blocks.
I never played the warhammer fantasy tabletop (I did play 40k, though it's been a long time since that and all the actual games were online through vassal), but I did read the rules and army books back in whatever edition was contemporaneous to 40k's 5th edition, as well spend a bit of time reading forum threads talking about the meta.
And that's about what I remember about Cold Ones: they're a really cool concept and design that just gets overcosted and has too many drawbacks.
In TW:WH2 they've got the same issues: too expensive, too slow, too many drawbacks, in a meta that heavily leaned into ranged spam, especially for Dark Elves who had one of the best and most spammable ranged infantry units in the game. Some armies relied on pitting enemies with chaff to slam with a hammer or rain tons of fire down on them, and for a few the chaff they pinned enemies with was also going to grind them down on its own, but others were just "kite and rain fire down on enemies, avoiding getting pitted" and Dark Elves were one of those.