Warframe perhaps

Brawlhalla

Guild Wars 2

Path of exile

Unturned?

Smite?
Dungeon Defenders 2?
Both free And Cool.

Castle Crasher?

About $1 on sale.

Brawlhalla (free to play, skins available for cash). Similar to Super Smash Bros, just on PC. Has local and online multiplayer. I'm not sure what's the player limit, since I've found the game just recently, but I've been able to play with 7 friends (4v4). While it is somewhat competitive, whether you win or loose, rewards are roughly the same, so it shouldn't cause any stress.

• Timberman
• Terraria
• Brawlhalla
• Lethal League
• Trine 2

The game I enjoyed the most with my friends is most likely Brawlhalla. I suggest you give that a try. :D

Payday the heist is fun and has a 4 pack special and is cheap when it's on sale which is pretty often iirc i bought the 4 pack for around $4

☞ Brawlhalla

Hm, that are some serious restrictions. I would have suggested No More Room in Hell but that one is First Person. Other than that maybe Devil's Dare of Fist Puncher. While they are not free you can get a copy really cheap on Tremor Games. But you have to invest a bit of time there. Although depending on your country this can be less than 10 minutes.

EDIT: The latter two may be local co-op only.

Castle Crashers is fun with 4 players.

Jackbox party pack is great for party games for 2-8 players, using one copy of the game and everyone uses their smartphone as a controller.

I might suggest Realm of the Mad God.
Though I wouldn't have suggested this in the past 2-3 years, the game switched companies and the new one has pumped out more content in 4 months than the previous one did in 3 years.
Pixel graphics, top-down, rogue-like, permadeath, lots of loot and grinding.
It does take a bit of time to get into, but the game's definitely more fun with friends. Calling out dungeons, sharing your rare drops etc.

I was gonna suggest Don't starve together, but the cheapest it can get is $10 single, $15 bundle (2 copies).. so $25 for 4 copy if you buy 1 bundle pack and one of your friend buys another bundle pack (you can only purchase bundle pack once per person)

so.. $25 for 4 copies? is that too expensive? (during sales)

Cards against Humanity: http://pyx-2.pretendyoure.xyz/zy/
Spyfall: http://spyfall.adrianocola.com

Aliens Swarm

dungeon fighter online? :p. tera?

Warframe might make you dizzy, be warned there can be a surge of colours, movement and action, even in third person. Not for the faint hearted at times.

Perhaps :

• Dragons and Titans is free, but it might not be up your ally. Neat little game though.
• Dying Light, can be dizzy perhaps if you have motion blur on and if you're parkouring a lot. It's not necessary though..this one is expensive.
• L4D2/L4D1 on sale.
• Trine 2/3, on sale. Only three players though..

Though before I go on to pretty much make another list again, I made a list in the past when I was looking for players to bond and play with but without much success. At least the list of games I have may be useful in your search. You can decide what you'd like from there. ^.^

Edit : Also this is not out yet, but looks promising in 2017. It's a game from the same studio that made Trine, it's called Nine Parchments.

Transformice?

Payday 2 Not that cheap on sale the 4pack is 15euro , worth the money !

Blood and Bacon?

Sven Coop?

Towerfall, Left 4 Dead, Trine, Worms!