You have two options to unlock this achievement. Both are going to take you 69 hours.
1. You can actively play the game on and off for 69 hours until the achievement unlocks
OR
2. Load up the game and just let it run in the background while you do other stuff. The game only needs to be running for it to count your playtime. You can track your playtime on your steam profile page.
Once the playtime hits 69 hours, your achievement should unlock.