The NeoAxis Engine just released the source code, although it’s technically not “open source” according to OSI compliant licenses. You can now access the source code on GitHub.
Here is the license:
- 1. When publishing your product, you must add "Made with NeoAxis Engine (www.neoaxis.com)" with the product information and in its credits.
- 2. You can distribute the NeoAxis editor with your product. When you do it the window title of the editor must be:
"Your project name - NeoAxis Engine 2020.3 (www.neoaxis.com)".
Or if you made engine modification:
"Your project name - Modified version of NeoAxis Engine 2020.3 (www.neoaxis.com)"
This can be done by changing the value of the ModifiedVersionOfNeoAxisEngine field in the Sources\Engine\NeoAxis.Core\Utility\EngineInfo.cs file.
- 3. You can distribute the source code of the NeoAxis Engine. In the case of publishing any part of the modified source code, for example, by means of creating a fork or other distribution method, you automatically become the contributor of the NeoAxis Engine. This means that the NeoAxis Group Ltd reserves the right to use your modified source code at its discretion, for example, to improve the original version of the NeoAxis Engine. Copyright for modified code is saved to you.
To me that certainly sounds like something an existing OSI license should cover. You can learn more about NeoAxis making the source available in the video below.