Here is the full list of all 14 Weird Hat Fight achievements.
Played on all maps
Played Orbit map
Collected 100 hats
Played Crafts map
Collected 50 hats
Collected 10 hats
Played Propeller map
Collected 1 hat
Completed 1 match
Played Arena map
Completed 10 matches
Completed 50 matches
Completed 100 matches
Play the game with 4 players