Here is the full list of all 27 Super Sanctum TD achievements.
Clear the Facility Compound
Kill 10 enemies with a single shot
Complete a level without using any skills.
Clear the Training Area.
Complete one level.
Kill 2 enemies with a single Bomb.
Get 100 perfect rounds.
Beat a wave with only skills and blocks.
Hit 10 enemies with Thunderbolt.
Kill a Walker with an Anti Air Tower.
Kill 10 enemies in a single Penentrator shot.
Have no blocks at the end of a level.
Clear Brightholme Industries.
Clear the Hydro Islands.
Kill a Huge Walker.
Unlock all tower and skill slots.
Kill a Big Walker.
Beat a level on Hard.
Beat all levels on Normal.
Kill the Patriarch.
Kill the Charger and all its clones.
Unlock all towers and skills.
Beat all levels on Hard.
Kill the golden Walker.
Get all stars in all levels on Hard difficulty.
Kill 10.000 Walkers.
Clear Elysion