All hidden items locations (there is 11 but only 10 are needed for the achievement):
1. In the bus stop around house number 113.
2. In jail, to the left from your cell, under the stairs.
3. In the Pawnshop in the first neighborhood. Against the wall, by some boxes.
4. At the fountain around 207
5. By the parcel lockers in the second neighborhood, behind the pawnshop.
6. At the fountain near 103 next to a stone wall.
7. By the fountain left of 206.
8. In the backyard of 206, behind the statue.
9. In the backyard of 201, next to a bench at the side of the house.
10. On the playground around 102/104, near the fence.
11. Near 114, if you circle around the property, there’s a bit with stairs and it’s down the stairs in the bin next to the bench there.