Either one or both works.
Mine is completing the Pokedex in the original Pokemon games. All you get is just Professor Oak giving you a wink and a small few second cut scene. And a congratulations text. Imagine spending all of your time then, getting all 151 and even 252 pokemon just for that? Yeah no thanks, I never completed the pokedex.
Going the Joja-Route in Stardew Valley. I say this mainly because, it is what you make of it. You forfeit being able to complete the Community Center by earning things, when you sign your soul away to Joja. What I would’ve liked is seeing Pierre go out of business completely. I just think that would add a route of depth in the game where you have to make ends meet through Joja because Pierre is permanently closed.
But, that doesn’t happen, he’ll still be in business despite his depression about Joja running things. Kindof ruins the whole concept of doing it for the achievements even.
I got one character to lvl 60 in Classic WoW Hardcore. When I got that last level up, I cried a bit. Very emotional journey.
I tried doing Ironman a while back. Not even on classic, just on whatever the latest patch was. It was only getting easier with time and I wanted my name on that leaderboard. In my mind, it didn’t seem like it would be that difficult as long as I played carefully.
I gave up after level 20. I didn’t die, but I had a few close calls and figured it wasn’t going to be worth it to grind out 90+ more levels using the worst gear in the game and no healing or stat boosting items.
That was an achievement.