Godot Engine - Feature-packed 2D and 3D open source game engine.
Construct 2 - Scirra Construct is a 2D game development engine with a focus on building games visually.
GDevelop - GDevelop is an open-source game making software designed to be used by everyone.
BYOND - BYOND is the premier community for making and playing online multiplayer games.
Defold Engine - Defold lets you quickly build high performing, cross-platform games together with your team.
Unity - The multiplatform game creation tools for everyone.