Here is the full list of all 20 Lichtspeer achievements.
buy all Lichtpowers
Score a 1000 headshots
Kill a 1000 enemies
get the I See The Licht artifact
buy first Lichtpower
get the Super Brillen artifact
Score a 100 headshots
Kill a 100 enemies
use a lichtpower for the first time
get your first artifact
get the Farspeer artifact
Score a 10000 headshots
Kill a 10000 enemies
buy everything in the Lichtshop
finish the game on normal difficulty
finish the game on normal+ difficulty
finish the game on rage quit difficulty
finish the game on rage quit+ difficulty
get UBER ratings for all levels on normal difficulty
get UBER ratings for all levels on rage quit difficulty