I present to you... The Wall of Walls!
You must sort these 64 words into 16 groups of 4 words. However, once you're finished with that, your mission is to build another wall with 16 new words, those words being the key word in each of those category names, and then solve it too!
For instance, if you grouped the words galaxy, kart, party and odyssey in a "words in the title of Mario videogames" category, you should use Mario as a word for the second wall (and maybe that would be part of the group "Nintendo characters" or "Names beginning with an M" in that wall). Don't worry, I think the word to be used for each category should be quite obvious (if it's the right group).
The only thing left to say is that only one of the words on the second wall is a plural. I clarify this because since you will be working with groups, the category names will probably be plural, so you should take this into account and use the singular form of the key word in all but one case.
Edit: Since the first Wall was pretty much solved, here is the 2nd wall, to avoid discrepancies:
post snake dragon android
rock amazon alien missouri
adobe police apple bird
google shape wall hitman
Although I've mentioned these in the comments, I'll add these here for clarification.
The word that should be in plural in the second wall is very fitting.
Stone instead of rock does work for the category I had in mind, but not as well.
The first category for the second wall was already found. The tags for the remaining three are music, movies and entertainment.
My other question on this site will pretty much tell you what one of the categories is (I made this before that one was solved, and I wanted someone to solve all of this first and then make the connection, but it didn't happen!)
The words in another category are supposed to be preceded by "the" (unless you choose the alternative word in hint 2. That word is... cooler).