So I've noticed a few achievements doesn't say how to get them, such as this one: Hexakosioihexekontahexaphobia I am a forum-posting beast! ^ It only shows the description but it doesn't say how to get it :/ I was wondering if there's a guide or something that tells me how to get achievements like this?

that Achievement is one of the very first ones in the oldest Achievement systems that Subeta had. It's super-retired, and shows up in the Legacy section. There's a new postsmonster Achievement now.

darn.. well thanks guys!!!

you are welcome.

How did I somehow get retired Achievements when I just joined? It says I have 46 of them...

Nevermind, maybe it was a bug, they aren't showing up anymore.