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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.

Godot Engine - The free and open source 2D and 3D game engine

Featuring gameplay that moves horizontally across a scrolling background, with characters typically walking, running, or jumping from left to right. Often includes platforming elements and side-view perspectives.

Unity is a game engine for 2D, 3D, AR and more