I recently released a toolkit for easily building 3D experiments in Unity Game engine with with my coauthor Dr. Nikolaus Troje. The toolkit, named bmlTUX, is free and open source. It makes creating experiments quick and easy with minimal coding involved. It's a great tool for speeding up VR and AR research. Learn more here: https://biomotionlab.github.io/TUX/
The toolkit includes tools to aid in both the design and the execution of experiments in Unity. The toolkit is designed to simplify the setup and reduce the required code needed to get experiments up and running quickly. The toolkit can automatically handle the difficult task creating trial tables, combinatorics randomization, blocking, etc. Such functionality removes one of the most difficult aspects of creating experiments. Additionally, using the included "Script Helper Tool", experiments work out-of-the-box, meaning that a runnable, simple experiment can be created with zero lines of code. Using more advanced scripting features, the toolkit can be customized indefinitely to provide custom functionality for complex experiments.
The toolkit was also designed to facilitate creating experiments incrementally. Variables and manipulations can be added or removed without requiring any changes to an experiment’s code, allowing for fast changes to test out new functionality.