what can you exactl do with a "MOD" instead of CS

[Romulator]

You can do almost anything as long as it doesn't require editing the .exe. There are certain ways to "go around" or try the next best thing (for example, you cannot make it so your character can swim, but can script him swimming instead).

The screen effects can be done, albeit, is a bit tricky. You'll be wanting to use Sanity Effects. DnALANGE did a tutorial on it. https://www.frictionalgames.com/forum/thread-22215.html Your Sniper Scope can be done with the same thing.