I've been reading a lot about entity-component design but every article talks about the philosophy behind such design, leaving a lot of details and implementations outside. I'm looking for an open source game that uses the entity-component design so I can study the concrete implementations and see how they deal with things such as How (and if) they deal with inter-component communication How much logic each component has or doesn't have How a subsystem can change it's behavior depending on an entity's state (the screen darkens depending on the player's health)