itch.io

Uses two-dimensional "sprites", 2D images created and used on a flat plane, as opposed to the three-dimensional models or environments found in 3D games.

Things that are available on GitHub

Products that involve or comprise source code, including programming games; does not refer to products with their own source code available, open source or not.

Sprites are generally 2D images used in games to represent objects. They can be animated or static, and come in different styles like isometric or top-down.