There are eight Costumes that are related to standard data of this video game, such as those are required to get that Achievement. Find those amongst Treasure Chests, and gain one once you have collected all standard 35 Memory Shards. Memory Shards are only there during night time. In each complex area is one to find, but none there is in Arkela Castle. Do not give up, you will see it - keep searching until you do! Just stand somewhere and turn around the camera - also look above you while turning the camera. You do not see anything - go to the next spot. But most of the Memory Shards are ultra simple to discover. If you wish to acknowledge how many you have already collected, see that information on the Map - hit BACK while free roaming. Related to each complex area, you will find perfect information about collectibles you have found and not found so far - when viewing the Map, under area title in an extra box. The last spot there is for a Memory Shard. Waiting until day time is over may be boring - perhaps you can go somewhere else in the meanwhile, and do something there - or, you just wait in free roaming going on onscreen and do something else not on Xbox 360, until the music stops and so night time starts. Sometimes it is advised to save game progression, so you can search the area again at night time if you have failed to discover a particular Memory Shard. When I did, Murphy's Law was working, and I have so finally discovered a rather good hidden Memory Shard - but that is what counts - success.