Batman: Arkham Origins
62 Achievements
1,300
40-50h
First Riddler Trophy
Collect every collectible
30
How to unlock the First Riddler Trophy achievement in Batman: Arkham Origins - Definitive Guide
Once you are in his HQ you'll want to make your way through the locked doors and find a green question mark straight across the balconies, use explosive gel on it and there the last (or first) Riddler trophy will be.
(Explosive gel is not necessary, you can be prompted to search instead - thanks VAN WILEY for pointing that out)
Video guide -
This trophy description is misleading. Only the collectibles for the 'Enigma Unravelled' are required, then one isolated collectible after. The Anarky tags and Pinkney Plaques are therefore not required. Once you have collected all 270 collectibles for the Enigma Most Wanted side mission, you will be prompted to return to his HQ. You'll find you are now able to destroy the PC, and the jammer preventing you from previously opening the adjacent door is gone. Hack the door, follow the path and press when you reach the wall with a question mark. Inside you'll find a riddler trophy like the ones in Arkham Asylum and City, and you'll unlock this trophy upon collecting it.
After you have found all 200 Enigma Items in Gotham City and have destroyed all 10 Network Relays in each district, return to Nigma's HQ in the Burnley district and proceed to the ground floor. You will now be able to bypass the sealed door near the computer terminal that was previously locked during your first visit. Once you have hacked the security code, enter the room and punch the green question mark on the wall on the far right. Pick up the Riddler trophy on the other side of the broken wall and the achievement will unlock.