In order to get this achievement you need to finish all of the tracks in the Flatliner Event.
To unlock this event you need to earn 135 medals along all the other events in the first place.
After that you need to finish the 7 Tracks listed in the Flatliner Event, those are:
- Truth is Out There
- Out of the Pit
- Fishy Business
- Dark City Run
- The Wreck
- Way of the Ninja
- Inferno 3
There's no easy way to get this Achievement.
Just like the extreme tracks in Trials HD, you really need to be good at this game to finish those nasty extreme tracks.
So practise and don't let those tracks get you down, one day you'll wake up and breeze through them like nothing:)
I've collected some slow-mo versions of platinum medals of the last seven tracks, all credit goes to the uploader and, far and foremost, the awesome riders in the video.
Maybe these videos will help some of you guys struggling to get past a particular obstacle.
Hfgl