Here is the full list of all 20 Strobophagia | Rave Horror achievements.
Activate the DJ's sound system at their beach setup
Take part of the opening ceremony of the Headless festival
Solve the impossibly cryptic riddle at Nax-05
Go back to the beach and help out your good friend CD
Complete the Gluttony ending
Complete the Avarice ending
Collect every picture
Connect to every wifi hotspot
Document the fate of Oedipa
Take a load off
Read the entire breakup thread at Siduris Lament
Complete the game without being killed or knocked down outside the beach area
Black out and wind up somewhere else while drunk
Get to the Quarantine on your own
Post the snap of any one character in 7 different threads
Complete the rites mural
Fulfill your blood-drenched potential with a grand feast
Try to hurt the horned monster
Be near 420 ravers as they get knocked out
Find the shrine to the horned monster