The first version of the Unreal Engine debuts with the release of the game 'Unreal'. It features advanced rendering capabilities and a modular architecture that allows for easier modding.

Unreal Engine 2 is released, improving upon the original engine with enhancements to rendering, physics, and AI. It becomes a popular choice for a wide range of games.

Unreal Engine 3 marks a significant leap forward, introducing a fully programmable pipeline and support for advanced shader effects. It becomes one of the most widely used game engines of its generation.

Unreal Engine 4 is released, featuring a completely revamped rendering architecture and a more user-friendly interface. It also introduces a royalty-based licensing model, making it more accessible to smaller developers.

Unreal Engine 5 is released, featuring Nanite (virtualized micropolygon geometry) and Lumen (global illumination and reflections), representing a significant advancement in real-time rendering capabilities. It aims to push the boundaries of visual fidelity in games and other applications.