As far as the knowledge of my gaming news concerns, and according to Wikipedia, Betrayer was released on Steam platform for PC in the month of March in 2014. I guess you can replace this game with some other new release. Some of my suggestions include Conan Exiles, Pillars of Eternity II: Deadfire, and Jurassic World Evolution. It is a nice effort you made, and it would be nicer if you keep it updated too.

Firstly, let’s agree that DPI/CPI or any customization that effects mouse performance is purely a personal preference. Doesn’t matter pro gaming or not.

Now, theoretically speaking, higher DPI and lower sensitivity is always recommended however some people preferred the opposite of it i.e. lower dpi and higher sensitivity. Also if are using multiple monitors or resolutions like 2560 x 1600, then higher DPI is a better option.

As for CS:GO case, we agree that most popular choice is 400 but people also prefer 800 (even above) once they level up. Low DPI usually helps in better aim but higher DPI helps you with speed. So once you get used to better aiming, the next logical step would be to do it quickly, hence the higher DPI levels.

For example, read the DPI preference on this thread & you can see our point 🙂
https://insider.razerzone.com/index.php?threads/dpi-settings-cs-go-deathadder.3163/

ignoring your ignorance, DPI settings based on several factors like screen resolution and sensitivity. Moreover it gives a gamer greater control over the mouse movement and acceleration. Here is a relevant thread for your understanding
http://www.tomshardware.com/forum/108877-13-gaming-mice-4000