A way to change difficulty mid-game

[Former user]

It would be very nice to have a way to change difficulty without having to start a brand new game.

I suppose this might be hard or impossible, but at least the request will be in the bugtracker for future reference.

[Frank Sapone]

There already is an unofficial way to do this. You can do "forcecvar skill <skill #>" in the console. The only affect this will have on the current level is the strength of your enemies. When you go to a new map more or less enemies will appear. If you use this method, do not submit bug reports. This is completely undocumented and for your reference.
However, I have been able to change skill level mid-game with this method and upon a new map transition the game worked fine.

There is no plans to make this like The Elder Scrolls: Oblivion where you can set the difficulty at any time.

Mara'akate

[Frank Sapone]

As described earlier from 2016-01-13 comment.