Here is the full list of all 25 Blair Witch achievements.
Become Carver
Break 10 totems.
Collect the first psychiatrist's note.
Kill 10 monsters.
Collect the first dog tag.
Walk 100 miles...
Pet the dog
Kill your first monster.
Collect the first victim's photo.
Collect the first wooden doll.
Help Ellis to get his redemption.
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
Pick up all the trash.
Collect all dog tags of the fallen comrades.
Collect all wooden dolls.
Collect all of the psychiatrist's notes.
Collect all victim's photos.
Let Bullet bring you 10 things
Score 40 points in Cobra.