Arduino IDE - Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware...
Unity - The multiplatform game creation tools for everyone.
PlatformIO - Next-generation IDE for IoT
Godot Engine - Feature-packed 2D and 3D open source game engine.
Visuino - Visuino is a visual programming environment that lets you write programs from Arduino circuit boards.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.