No missable achievements (plus 19 unknown)
Sign in with Steam or Xbox to track your progress, and:
Finish the prologue.
Leave the office building.
Find the principal.
Explore the library.
Go to the nurse's office.
Search the auditorium.
Search the basement.
Check out the dorms.
Enter the gardens.
Cross the gardens.
Finish the game.
Kill 3 monsters with a single light grenade.
Every playable character survived at Leafmore.
Finish the game in 'Normal' mode.
Find all of the weapons.
Kill 150 monsters with a firearm.
Finish the game in 'Special' mode.
Finish the game in 'Hard' mode.
Kill 50 monsters hand-to-hand.