How exactly is it calculated? Because according to the UI I have 200% crit chance and I barely ever crit... At default settings with 100% I crit even less. feels more like 10% instead of 100% tbh. Is not every shot calculated for crit?

Per-level setting for Critical Chance seems to be unused. As such the default crit chance for each hit is 1/200 = 0.5% per level (0,01(1)% for fire damage). This applies only to damage dealt by a character, with damage type that is not "poison" or "cold". Critical damage is also affected by stat level, a multiplier 5 + 0.5 per level - this, with current crit chance calculation, will give you +45% DPS on level 10, +2700% DPS on level 100.
Anyway, while it may seem unbalanced, it is an, easy to fix, bug.

Made some changes to critical hits. New version released