Thief
37 Achievements
1,000
40-50h
More Heist Less Speed
Finished the game in 15 hours or more
30
2.46%
How to unlock the More Heist Less Speed achievement in Thief - Definitive Guide
You can beat the game, and replay the level at a later time to unlock this achievement. I recommend completing the chapters, then working on Client Jobs and Side Quests within The City. After completing them, you can also idle your character in a safe location in The City to help build up time.
Once the menu timer reaches 15 hours, you can replay Chapter 8 by visiting the South point of Grandmauden. Once you complete the level, the achievement will unlock.
i finished chapter 8 with around 13 hours on the timer.
This should come naturally if you take your time, complete all the side jobs and go for all the collectibles. You can check you total playtime in the Player Progression section of the menu. If you are approaching the end game and are still somewhat short you can leave your game idling for a few hours to make up the difference.
NOTE: If you do complete the main story short of the fifteen hour mark it has been confirmed that you can go back out into the city, finish up anything you need or simply idle to pass the time, then go back and complete Chapter 8 again to unlock the achievement.
You must acquire a total of 15 hours of gameplay time to unlock this trophy. Replaying Chapter 8 once you've beaten the game already will unlock this trophy if you have accumulated the 15 hours of play time. The last chapter in Thief is Chapter 8. If you've followed our suggestion in the roadmap about doing everything you possibly can on your first playthrough, you should have no problem getting over 15 hours of playtime. You can check at any time how many hours you've played through the main game menu, when you're hovering over your save file or the "continue" option.
Of course if you want to just leave your console running so you can get the 15 hours like so, you are welcome to do that as well. Simply find a roof and leave Garrett idle there so he's safe from harm.