Impossible lost Achievement regret?

[Reiki Knight 13 1,467]

Whether it's due to online features gone  a game dlc no longer available, or broken game/glitches have you ever had an achievement you really wanted but failed to get before it was permanently locked out of possibility?

For myself it was telltales game of thrones I didn't have the money for the extra chapter and by the time I did it was gone so I only have chapter 1 achievements on my 360.

And now the game is literally impossible to get.

[Deae Rising Shine~ 52,453]

Certainly was onine trophies that weren't too bad to get, but I was busy with other games. And now servers are closed. Like WipEout HD for example. And some DLC that aren't sold anymore.

[Reiki Knight 13 1,467]

Not so much impossible but just difficult is my trying to get the Richter achievement in Castlevania sotn. He is such a glass canon it's HARD trying to get through the inverted castle part. Every little hit does so much damage it's absurd.