Here is the full list of all 25 Blair Witch achievements.
Pet the dog
Collect the first psychiatrist's note.
Collect the first victim's photo.
Collect the first wooden doll.
Help Ellis to get his redemption.
Become Carver
Find out what happened to Bullet.
Find out what happened to Peter.
Patch things up with Jess.
Pay your respects to sheriff Lanning.
Let the VA know about the lumberjack's death.
Make the pizza guy lose it.
End the game without killing any monsters
Kill your first monster.
Kill 10 monsters.
Pick up all the trash.
Collect the first dog tag.
Collect all dog tags of the fallen comrades.
Collect all wooden dolls.
Break 10 totems.
Collect all of the psychiatrist's notes.
Collect all victim's photos.
Let Bullet bring you 10 things
Walk 100 miles...
Score 40 points in Cobra.