Flame is a modular Flutter game engine that provides a complete set of out-of-the-way solutions for games. It takes advantage of the powerful infrastructure provided by Flutter but simplifies the code you need to build your projects.
It provides you with a simple yet effective game loop implementation, and the necessary functionalities that you might need in a game. For instance; input, images, sprites, sprite sheets, animations, collision detection and a component system that we call Flame Component System (FCS for short).
The documentation webpage can be found on this website.
You can see a demo video from the youtube official.