Here is the full list of all 28 Stick Fight: The Game achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Finish a round on each map of the game
Kill an opponent with a mid air kick
Become the target of a snake and survive the round
Headshot
99 total kills
Win a round by every opponent falling off the map
Kill 3 other players in one round
kill 3 other players in one round without taking damage
Win on every level
Win on a match where a black hole appears
Kill 2 other players within a short amount of time
Kill 3 other players within a short amount of time
Kill 4 in a row without dying
Kill 5 in a row without dying
Kill 6 in a row without dying
Kill 7 in a row without dying
Kill 8 in a row without dying
Kill 9 in a row without dying
Kill 10 in a row without dying
Get killed by a snake
Win by reflecting a bullet with the block
Block your opponent then immediately kill them with fists
77 sniper kills
Kill an opponent with the last bounce of the bullet of the bounce weapon
Win the round after all ice is destroyed on an ice-level
Win a round by killing 3 opponents using the blink dagger
All other achievements
Pick up a Light-sabre