Here is the full list of all 16 Tetradecagon achievements.
Beat the highest level, Icosagon.
Enable epileptic friendly mode.
The illusion of allusion.
Suck 500 times.
Beat your highscore 50 times.
Use the Konami Code.
Die 100 times.
Beat your highscore 10 times.
Lose control of the ball seconds immedietely after bouncing it.
Glitch the ball out of the polygon.
Beat your highscore.
Perform a 360 while bouncing the ball.
Perform a 540 while bouncing the ball.
Die 5 times on one level without progression
Die for the first time.
Die immediately after the grace period on the first level.