Here is the full list of all 38 Lethis - there are Daring Discoverers achievements.
Complete Yllion using the way of secrets
Complete Yllion using the way of the warrior
Complete Yllion using the way of the diplomat
Complete Yllion using the way of the warrior or diplomat, and also having completed the way of the secrets
Complete Vendemelle using the way of the warrior
Complete Vendemelle using the way of the trickster
Witness Vendemelle's artefact teleport itself three times
Get all the deaths on Anbar
Complete Anbar
Allow Monique to die on Anbar
Allow Gilbert to die on Anbar
Allow Bertrand to die on Anbar
Allow Rose to die on Anbar
Allow Rutherford to die on Anbar
Meet yourself on Azimut
Defeat the monster on Azimut
Complete an alphabet
Complete a planet without ever dying
Find the body of a previous explorer
You have waited patiently for Godot on Yllion
Win the race on Vendemelle
Fall from the temple on Vendemelle
Die by your own hand on Azimut
Kill yourself on Azimut
Die a second time confronting the Azimut monster
Manually trigger an alert on Ultima
Complete the alphabet of the parasites on Ultima
Take at least three different useless objects
Complete Ultima using the way of the saboteur
Complete Ultima using the way of the machines
Destroy seven guards on Ultima
Use the elevator on Ultima
Complete all the alphabets
Complete Magofu
Talk to the golem on Magofu
Congratulations! You have finished the game!
Complete the tutorial
Die on Magofu