Cold is a unique attribute in Elex - it determines how much humanity is left in the hero. In the beginning of the game this attribute is at neutral level. However, Jax's decisions which he makes throughout the game, can change it. You can check your current Cold level in character sheet screen (the picture above).
In a nutshell - empathizing with NPCs during conversations lowers your Cold and you get "good karma". Selecting dialog lines during which you act cold and without any emotions increases your Cold which means that you get "bad karma".
It is recommended to focus only on those dialog lines that either lower or increase your Cold and stick to that choice throughout your entire playthrough. The game informs you about every change in Cold:
- The first picture shows an example of lowering your Cold.
- The second picture shows an example of increasing your Cold.
Warning - "Protecting yourself" from selecting a wrong dialog line by accident is a very good idea. Try to save your game before you start a conversation. Reload the game and repeat the dialog if you acted in a wrong way, when your Cold stayed on the same level or it changed in an undesirable way.
Cold is only symbolic in the initial stages of the game. However, it becomes important when you make enough progress in the game, especially in the main storyline. During some of the important dialogs you can notice that certain dialog lines can't be used by you if Jax's Cold is too low or too high.
An example of that situation is presented in the picture - the only available lines are no.1 (for a hero with low Cold) and 2 (neutral dialog line) while the line no.3 (for a hero with high Cold) is blocked.