There are 9 different deaths required for this achievement, some of them are early in the game and some are near the end. If you missed one of them you can choose the area from "New game" in the menu to get it.
Listed by earliest:
- Running out of oxygen (from the very beginning if you stand still you will die)
- Falling to death (can be done from the start when you jump to the boulder that collapses)
- Crushed by rocks (further along the first mission boulders will fall so make sure to die to them)
- Killed by the tornado creature near the tall building in town (after the town area you will encounter a tornado, allow it to kill you)
- Activating bomb and getting blown up by it (after the town you will be underground, you will need dynamite to blow open a door. Put it down and stand next to it)
- Stabbed by the plants (starting in the wasteland you will have a short cutscene showing how plants can kill you, from then on you will encounter these plants often, simply walk over one and instant death. They are found in most later missions
and shoot out of the ground, impaling you in the process)
- Grabbed by the flower tree (you'll encounter these flowers alot throughout the game and you'll know what they are when you see little blackish spikes sticking out of the ground, they swallow you whole and can be found easily in Nightfall and The Portal. Simply walk over them)
- Getting burned by the lava (in the last level Inferno you need to burn to death so either jump into the lava below or land on it further in)
- Platforms in the middle of Dead Forest and also on Cliffs (If you stand on them long enough they will kill you)
The fans in the Research Facility do not count towards the achievement.