Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Unity - The multiplatform game creation tools for everyone.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.