SpatialOS is a cloud-based platform developed by Improbable that enables developers to create large-scale, multiplayer games and simulations. It allows for the seamless integration of numerous game elements and players, providing a framework that can handle complex interactions and vast virtual worlds. By distributing game logic across multiple servers, SpatialOS ensures that performance remains stable even as the number of players increases. This technology supports various genres, making it easier for developers to build immersive experiences without being limited by traditional server architectures.