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 "I'd Like To Have That In Writing" relic challenge.
Complete "Urnique" relic challenge.
Complete "The Most of Us" relic challenge.
Complete "Retcon" relic challenge.
Complete "Time Waits For No One" relic challenge.
Complete "Splinter Cat" relic challenge.
Complete "It'd Be Too Damned Easy" relic challenge.
Complete "A Quiet Place" relic challenge.
Complete "Well Planned!" relic challenge.
Complete "If It Is Broken, Don't Fix" relic challenge.
Complete the story of Timelie.
Complete "Omen" relic challenge.
Complete "Operation Skuld" relic challenge.
Collect the 4th Memento.
Collect the 3rd Memento.
Complete "I Come in Peace" relic challenge.
Complete "3-2-1-GO-1-6-7-8" relic challenge.
Collect the 2nd Memento.
Complete "This Is Cat. Can You Hear Me?" relic challenge.
Collect the 1st Memento.