Here is the full list of all 35 Planet of the Apes: Last Frontier achievements.
Complete Prologue
Where have all the good guys gone?
Best of all outcomes
Jess betrays confidences
Jess puts her life on the line
Jess and Bryn sitting in a tree
Apes together strong!
Damn dirty apes
Complete Chapter 1
Complete Chapter 2
Complete Chapter 3
Complete Chapter 4
Bryn is his father's son
Bryn demonstrates brotherly love
Bryn shows wisdom
Bryn is a family man
Juno's downfall
Bryn shows his true colours
Bryn prefers deeds to words
A debt repaid
Bryn opens the way to peace
An explosive ending
Jess looks a gift horse in the mouth
Mark demonstrates his feelings for Jess
Maria accepts her fate
Jess puts the big man in charge
Jess does the right thing
Jess does what's necessary
Thaw relationship with Mark
Bryn covers up a mistake
A chilling ending
Bryn makes an important choice
Bryn shows no mercy
Set an ape on fire
A rather pointed decision