Ai Snake

Create a basic game engine structure in Clojure that implements a minimal Entity Component System (ECS) framework. I need functions to manage the world state, including creating entities, adding/removing components, and querying for entities possessing specific sets of components. The core functionality should include methods to register systems and to run a 'tick' function that executes all registered systems sequentially, passing the world and a delta time. Please provide the API definitions for functions like `(new-world)`, `(create-entity)`, `(add-component ...)`, `(entities-with ...)`, and `(tick ...)`.