Since I was talking about the project in the Reflex Discord recently, there was a request to show what I had. So, this is my project I've been working on for a few months. It's built in UE4 and the general idea is to provide an environment where you can mimic the weapons/opponents of a wide range of games.
http://store.steampowered.com/app/824270/KovaaKs_FPS_Aim_Trainer/