Unity is published by Unity Technologies. This page compares only projects with an explicit relationship to it; shared categories alone never create an alternative claim.
Recommended order uses OpenAlternative organic alternatives v4 (version 4). Relationship confidence, category fit, logarithmic popularity, as-of maintenance and freshness, bounded anomaly quarantine, and known-data penalties. Payment is fixed at zero.
A hard constraint removes a Project only when its stored fact is known and conflicts. Unknown facts remain visible, are called out below, and never become a negative claim.
Free 2D and 3D game engine with no royalties
Godot ships a complete engine, editor, and export pipeline under the MIT licence, which means no royalties, no revenue thresholds, and no licensing conversation before a project starts.