Unity

Page

Unity is one of the easiest game engines to develop with on the planet. It’s also one of the most powerful.

Free for low profit developers — You can upgrade to pro for around 75$/month but thats probably only worth considering if you have a serious project with some hope of ROI —  you can potentially get yourself into the industry with very small investment or even use it for other non game projects that require audio/visual/interactivity.

https://unity3d.com/

Many of the posts on this site are unity related. Unity makes great use of c# as its scripting language of choice. Throughout this site you will find snippets of code which may be useful.