Searching the best of 10 Local 4 Player Games (koop/vs)

Screencheat is a good 4 player one, Nidhogg and the MK games are good 2 player games and they both have tournament modes so I guess they could be considered 4 player.

Isaac Rebirth has 4 player co-op but I never tried it.
Mortal Kombat has a decent one.

and... Fifa for sure haha.

SpeedRunners !!!
Definitely worth the money :-)

incoming text dump;: list of local co-op & party games:

screencheat, gang beasts, duckgame, towerfall ascension, nidhogg, sportsfriends, lethal league, samurai gunn, brawlhalla, knight squad, mount your friends, speedrunners, crawl, thief town, cloudberry kingdom, expendabros, brofroce, keep talking and nobody explodes, charge shot, rocket league, battleblock theatre, super time force, monaco, dustforce, hammerwatch, monaco, fistful of gun, westerado

Torchlight II is a little aged, but it's still an excellent co-op experience, especially with mods.
Hammerwatch gets an honorable mention due to its charming graphics, but the gameplay can get rather stale at times.

Guacamelee! Super Turbo Championship Edition can be played on 4players

Played Gang Beasts at a friends and had a great laugh. Can see it getting boring though

There is actually a tag on Steam for 4 player local multiplayer if you need it.

And to add a title nobody mentioned yet - Rayman Origins is pretty fun with friends. And Jamestown - it was a surprising for me how good it works in co-op.

Gauntlet maybe?

I love coach games, btw what is that bbt forced for 4 players?

The ones that comes to mi mind are:

Shoot many robots
Crawl
Samurai Gun
Nuclear Throne is 2 players but is going to be 4 players i think
Hammerwatch
Abyss Odyssey
Bloody trapland
Gang Beasts
Broforce
Castle Crashers
Forced
Friendship club
Figthies
Gauntlet
lara croft and the guardian of the light
Lethal league (really fun)
Magicka
Miner Warfare (i think you can even play 8 coop)
Nidhogg (only 2 players at one, but have to mention it, sorry)
Rayman origins and legends (really greats)
Road Redemption
Screencheat
Speedrunners
Sportsfriends
Starwhal
Towerfall Ascension (one of my favorites)

And if you dont mind to emulate:

Super Smash Bros
Mario Party
Mario Kart
Crash Bash

Most of these have already been named, but these are my Favorites:
Brawlhalla - F2P Smash Bros Clone
Gang Beasts - Fun Phsysics based Brawler, playable with ( from what i've tested) at least 6 players
Brawl - Great Bomberman-Type game
Quiplash - Kind of like Cards against humanity, Played with Smartphones as controllers(up to 8 players)
Towerfall Ascension - Another Fun 2D Arena Brawler with Coop "Story"- Mode
Spelunky - Randomly generated Digging/Platformer Game
Sonic & Sega All-Stars Racing Transformers - Good Mario Kart substitute
Octodad - Definitely not an octopus
Screencheat - splitscreen fps where you have to look on other players screens since you're invisible
Rocket League - Soccer with Rocket Cars!
Castle Crashers - Great Beat Em Up

Some already mentioned but awesome:

Crawl
Towerfall Ascension
Brawlhalla
Samurai Gunn
Lethal League
Sonic & Allstars Racing Transformed

Not mentioned yet:
Hidden in Plain Sight - Stealth / sneaky local multiplayer game. Fun and cheap!
Clusterpuck 99 - Up to 8 players
Worms Reloaded (Worms Armageddon is better, but doesn't support gamepads natively)
The Jackbox Party Pack 1 & 2 - players use their phones as controllers

Bundled:
Retro Game Crunch
Chargeshot
BRAWL
Grand Class Melee 2
Jamestown
Gish (though the new version 1.7 seems pretty broken, try to get 1.6 instead)

Move or Die

Just released and is centered around local 4 player action. Can play online as well. Highly recommend.

From the store page link that Tyrogus brought up, here are some games which I personally liked playing, or owned because I thought they looked nice, and that were not already mentioned, that I think would be great fun in mulltiplayer:

Straima
Toto Temple Deluxe
Shutshimi
Phantom Breaker: Battle Grounds
Soccertron
Legend of Dungeon

I see someone mentioned Lara Croft and the Guardian of Light, the coop is great but that one is only 2 players if I remember correctly.
The second one, Lara Croft and the Temple of Osiris allows 4 players coop and I found it really fun too