How do you organize your library?

Backlog
finish but have archievements left
finish
finish without archievements
boring
and then all other games

Favourites (I put endless games in here that I currently have installed.)
Complete (100% finished)
Finished (I beat these, but could still go back to to 100%)
Gave Up (I played at least ~3 hours but didn't finish and don't want to currently.)
Multiplayer
Unfinished
My Games (At this point I leave new games here and install them right away to play. I'll move them to the appropriate category after playing.)

I also attached an image of how I used to do it. I loved having lots of categories like that but they started to feel irrelvant to me after some time, so now I sort them mostly by progress.
The friends categories are because I used to give each of my friends that I played games with their own category with the multiplayer games that we had in common.

View attached image.

I do:

• Currently Playing
• Early Access
• Multiplayer Only
• Unbeatable Games (i.e. no campaign, excludes multiplayer only games)
• Games I need DLC for (usually only DLC that adds story)
• Beaten
• Everything else

currently my categories are

• - Awaiting New Content
• - Currently Playing
• - Finished
• - Finished But Replayable
• - Priority To Play
• - Steamgifts Wins
• 1st Person Adventure Game
• 1st Person Modern RPG
• 3rd Person Adventure Game
• 3rd Person Modern RPG
• Actiony
• Classic Isometric RPG
• Exploratory
• GTA-ish
• Misc
• Platform Puzzle
• Platformy
• Puzzle
• Strategy
• Unsorted
• Visual Novel

Favourite, Backlog and everything else.

I should probably add "Finished" too, but I don't feel a need. Game is either excellent and goes to favourites, or not that great and forgotten forever :3.

View attached image.

I have deja vu, but here it is
"Games to play"
"Games played and to play again"
"Games played and never to play again"
"Freebies"
"Won Games"
"Installed"

I have:

• Favorites (collapsed)
• 100 % (collapsed)
• In process
• No chivs (collapsed)
• No chivs, card (collapsed)
• Queue
• Games
• SteamVR (collapsed)

Favorites, Games and SteamVR are default/automatic categories.
100% has those games I've -- you've guessed it -- completed.
In process has the games I'm actively playing. Actively meaning loosely "I should finish this before starting something else" or "must grind the last achievement tomorrow". All installed.
No chivs -- games with no achievements and no trading cards. Also has a couple of games WITH achievements. In those cases the achievements are broken or "impossible" to get -- they are listed here so I won't accidentally start them and flip any desks.
No chivs, card -- games with no achievements, but with trading cards. Also has games I've 100%/otherwise completed but should farm for cards.
Queue -- games I'm meaning/wanting to play ASAP/tomorrow. Flexible. Sometimes games from In process move here if I have no immediate spark to finish/play them. Sometimes games go back to Games. Some already installed, most not.
Games -- games I'm yet to play, for whatever reason. Usually has no installed titles.

• I hide the games I'm not interested in playing. Like certain free games or games that are a part of a series but I'm missing the others.

ETA: the pros and cons! Con is that I sometimes forget which games are which -- is "Last Federation" SIM, 4X, RPG, puzzle? I also tend to browse through stuff a lot and keeping my Queue "fresh" takes some time. Pro is that I always know where I'm at and which games are a priority. I'm obsessed with chivs and completions, so... Also, if I need quick cash, I can always farm the No chivs, card section empty without worrying about accidentally triggering any chivs (like play at a certain time).

• Backlog
• Games I completed
• Racing Games
• Flying Games
• Indie Games
• AAA Games
• random crap I dont even know about why it is in my library (free weekend, f2p etc)

I have only 'favourites' and the rest is in one big list.

I just hide everything I am not interested anymore.

I use categories based more on Steam features provided than game content itself, including what I've "completed" with some games, and some overlap:
Achievements
No Achievements
Soundtrack
Badge 100%
Foil 100%
Achievements 100%
Beta
Cannot Be Played (reserved for games that cannot be played by anybody, servers disabled, etc.)
DOSBox
Early Access
Purchase Disabled
Removed From Store
Trash
Workshop
Free 2 Play
Non-Steam Game

I organize my library by genres. I also have a finished games category and a "hell no" category for games I won't play.

How I organize:

View attached image.

I have 3 catagories I use. Installed, Not installed, and finished.

Completed for games I beat the main content for. Favorites. Completion for 100% cheevos. Multiplayer for games strictly for said act. And uncategorized for uncompleted or untouched games. I still want to further catagorize but am too lazy :3

(This is how I organise it, but you know , that's just how I do it)
All Games
All Games Downloaded
Completed
EarlyAccess
Games From Friends
Multiplayer
Must-Download
Must-Play
Needs DLC First
Not Downloaded Yet
Now Playing Current
Now Playing No End
Short Games
Free Games
Write Reviews For

My categories are:

100% (either in game or steam achievements (or both))
3D Realms (just because I got a huge bundle of those games)
Backlog (pretty obvious what it does)
Backlog playing (this is for when I pick a game from my backlog to play through, usually during holidays)
Finished (obvious)
Good Games (games that are good in my opinion, can be finished, installed or whatever)
Installed (games I got installed on my gaming pc)
Installed laptop (games I got installed on my laptop)
Needs checking (usually the games I get (from bundles, wins or whatever) first go in here until I decide where to put it (installed, backlog, whatever))
No categorie (most of these are 'trash' games I don't care for)

And then there are some categories for different bundles which had a lot of good games, just to be able to find them quickly.

For me, this system works great. I can easily pick a game to play by just looking through the installed category. If I want to install a new game, I can check backlog (or needs checking). If I ever want to play a great game again, I can check good games. Etc, etc.

I just organize whether it's singleplayer or multiplayer.

Mainly sorted by origin on which I prioritize the games I play. Playlist is a list of games I wanna start playing or actively try to beat, Unfinished sorts games I have dropped and have to pick up again and Multiplayer is obvious.

View attached image.

Favorites
Action
Action-Adventure
Adventure
Aufbauspiel (e.g. Sim City 4 Deluxe)
Casual (Most games go in here, like shoot'em ups, etc.)
FPS / 3rd Person
Hack'n'Slay
Hidden Object
Jump'n'Run (Platformers)
Open World
Puzzle
Racing
Random Gore (e.g. Carmageddon, Dead Rising, etc.)
RPG
Simulation
Sports
Strategie/Rollenspiel
Tower Defense
SteamVR

I cant really understand why steam hasnt even implemented a basic filter option for the library yet. So many people with hundreds or thousands of games nowadays.

I want something like this site. http://www.lorenzostanco.com/lab/steam/

That can't be to hard to program.

General and Misc. Misc being games I have not played or don't like.

favorites for all steam games
leeched :3333
won on sg
games for non-steam apps

View attached image.

"Achievments to go" "Done"
Maybe I will add later on a "Has no achievments" to have it easier to check if some games get some afterwards