Throughout the Neighbor's house, especially in Act 2 and 3, you'll find various items that don't directly contribute to puzzle solutions but offer glimpses into the Neighbor's backstory. These can include photographs, children's drawings, old toys, or newspaper clippings. While not tracked as formal 'collectibles' with a counter, interacting with them often triggers a brief visual or audio cue, adding to the game's mysterious narrative.
For example, finding certain family photos might reveal details about the Neighbor's lost family members. Discovering specific toys could hint at past events or traumas. These objects are often subtly placed in less-traveled areas or behind minor environmental puzzles. Taking the time to explore every nook and cranny can significantly enrich your understanding of the game's lore, providing context for the surreal environments and the Neighbor's erratic behavior. There's no achievement for finding them all, but the narrative payoff is significant for lore enthusiasts.