Here is the full list of all 15 Arma Reforger achievements.
Placed 20 mines in any official game mode, on any official server.
Delivered 5000 supplies to friendly bases in a single Conflict play session.
Interacted with a pipe organ in any game mode.
Interacted with a piano in any game mode.
Flushed a toilet in-game.
Destroyed 25 enemy vehicles.
Finished the tutorial with every available task completed.
Neutralized 100 enemy players in any official game mode.
Achieved the rank of major in a single Conflict play session.
Finished the Combat Ops scenario with every available task completed.
Delivered the enemy intel to the extraction point in the Combat Ops scenario.
Killed 10 times by other players in any official game mode.
Used a medical item to assist other players 50 times in any official game mode.
Neutralized 500 enemy players in any official game mode.
Used a medical item to assist other players 250 times in any official game mode.