Gameplay Assemblage begins with the protagonist waking up inside an experimental mechanism. The machine was created to restore memories lost due to accidents. Finding himself inside a parallel world and his own mind, the protagonist is overcome with fear, he does not know how to get out of here, and what awaits him in the future. He does not remember why exactly he entered this device, but the voice of artificial intelligence helps him get on the right path.

Asemblance only supports a single-player story mode with a first-person view. The atmosphere and environment are presented in a dark style with elements of horror and horror. The central character tries to escape, and on the way he encounters events from his own past. He does not want to see most of the memories, but they become more, which is why the hero gradually begins to go crazy.

The user has to figure out what is real among the memories encountered while exploring a parallel world. The character is unable to figure out which memories are his own and which came from other minds. The main task is to understand why he came from here and how to get out of the mysterious dimension filled with secrets and horror. In the process, the gamer is able to interact with the environment, read notes and open passages.