Here is the full list of all 20 Will Glow the Wisp achievements.
I was just kidding, you know irony?
Okay you won, why I give you an achievement for this escapes me
Becoming an adult means understanding that the time for games is over
You realize how easy it was to be a child
It is finally legal for you to make your own bad decisions
You are feeling ecstatic for having experienced what just happened
Starting to get along with the other sex
Becoming a teenager was hard, but you made it
You are realizing that not everything is a game
Don't you think killing him went a little to far?
That was not what I intended
Expanding your horizon
I wanted to create a secret level for this, but a hidden achievement and your pride have to be enough
How did you figure that out?
That was an important milestone in your development
Sometimes standing still is harder then moving
It can move, how amazing!
Faster than another human being, well he was not that good...
A new wisp is born!
Impressive, now you only need to do that 56 more times