Here is the full list of all 22 Samurai Survivors achievements.
Slay 10.000 Spirits
Betray your clan and get the curse of undying
Slay 100.000 Spirits
Slay One Million Spirits
Reach Age 100
Reach Age 150
Collect 1000 Souls
Collect 10.000 Souls
Collect 100.000 Souls (Do you really need that many?)
Survive 15 minutes
Survive the first stage of Curse of Undying
Survive all 5 stages of Curse of Undying
Survive 15 min without getting hit once
Survive 15 min without moving at all
Survive 15 min only using your starter weapon
Reach max walking speed
Reach max posture
Reach 50 level in a technique
Fully upgrade a technique
Reflect a fatal damage
Unlock "Forbidden Lands"
Unlock "Eastern Castle"