Unity3d builds the app and scripts are written in C#. It receives first class support from the Unity3d developer and most plugins exist in C# in comparison to Javascript (the other supported scripting language)

I use Git because there is nothing else that seems better for backup and working with other developers. However, the learning curve is high and there are times when non-developers must also know how to use git.

Easy, secure, and reliable access to files among collaborators accessible from most devices

It's free and served from a local network server

Added and built-in support for debugging Unity3d applications. Intellisense is also great.