The Chapter 2: Family Secrets Add-on for Tell Me Why has 10 achievements worth 500 gamerscore.
Find three classic posters
Prove to Tyler that moo boxes are actually funny
Stick a note on Tyler's back
Complete Episode Two
Make peace with Mary-Ann at the cemetery
Win the plushie battle
Discover intel about Mary-Ann's past and her death
Find a recording of the twins' 911 call
Correct the old graffiti on the tree
Figure out who inspired each Book of Goblin character