Game engines provide a software framework for developing games across multiple platforms. They include components like a rendering engine for graphics, a physics engine, tools for in-game sound, scripting, artificial intelligence, networking and more. Popular commercial game engines like Unity and Unreal Engine are used widely by developers to build games efficiently. The rendering engine converts 3D models to 2D images using the GPU, while the physics engine simulates real-world phenomena through calculations from the CPU. Scripting is also important for programming game logic and artificial intelligence. Overall, game engines aim to deliver a unified development platform for creators.