Chivalry 2.

No ranked mode and you can put in as much effort as you want.

The game is easy enough to pick up and run into a group and spam and get some kills and have some fun.

Learning the mechanics makes you better than 85% of players and allows you to top the scoreboard. If big battles aren't your thing there are also 1v1 and 3v3 duels.

You can be as competitive as you want without the stress of having to be a try hard in ranked.