There is no easy way to develop game apps in WP8 with C# code using a framework like XNA
http://www.monogame.net/ and https://unity3d.com/ are two great, easy to use engines. Unity does support WP8 and UWP. Monogame does as well (https://www.rizamarhaban.com/2015/08/29/monogame-uap-uwp-for-windows-10-build-10240/).
There are other game engines but I just am referencing, I just picked two that are well known.
I have got a lots of Ideas about the games because I love car racing and I would love to develop my own gaming app.
Yes need better tools to develop games