Here is the full list of all 22 Timelie achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Watch the secret ending.
Obtained all Timelie achievements.
Complete "Operation Skuld" relic challenge.
Complete "Time Waits For No One" relic challenge.
Complete "Retcon" relic challenge.
Complete the story of Timelie.
Complete "Omen" relic challenge.
Complete "I'd Like To Have That In Writing" relic challenge.
Collect the 4th Memento.
Complete "Urnique" relic challenge.
Complete "I Come in Peace" relic challenge.
Collect the 3rd Memento.
Complete "The Most of Us" relic challenge.
Complete "Splinter Cat" relic challenge.
Complete "It'd Be Too Damned Easy" relic challenge.
Complete "3-2-1-GO-1-6-7-8" relic challenge.
Collect the 2nd Memento.
Complete "A Quiet Place" relic challenge.
Complete "This Is Cat. Can You Hear Me?" relic challenge.
Complete "Well Planned!" relic challenge.
Complete "If It Is Broken, Don't Fix" relic challenge.
Collect the 1st Memento.