Assassin's Creed Syndicate

To reach 100% completion in the "Jack the Ripper" DLC you have to do EVERYTHING. Complete the main story missions and their optional objectives, complete all associate activities and their optional objectives, and collect every chest, Helix glitch, and illustration. Luckily maps can be purchased to find the illustrations and chests in the sandbox, and Helix glitches show up on your map. Still, the collectibles part can be a bit tricky because chests and Helix glitches appear in main missions areas (Owers Manor in Memory 4, Deptford Prison in Memory 6, Lambeth Asylum in Memory 10). If you want to get the trophy on your first playthrough, be sure to check your map in these areas and grab all the collectibles before you hit the point of no return in the memory.