Milestone 6.26.0 Released! (Experimental) — Xenonauts 2 Steam update #391629

This update is also only accessible by switching to our Experimental branches (instructions on how to do so here) - although please be aware they have slower load times and worse performance than normal builds due to the extra logging they contain!Gameplay Changes:Operation Points can now fall below zero and turn negative if you pay the UFO Delegation cost while not having enough OP available to cover it.Temporarily removed the air combat ambience track, as some people were complaining it contains a painful high-pitched whine that makes the air combat almost unplayable. Sadly I'm in my late thirties and I apparently lack the auditory range to be able to hear this (ouch), but we'll add the sound back in once our sound engineer has had a chance to strip out the offending whine.Added a tooltip for the UFO Delegation campaign option that explains what the system does.Removed the obsolete "Ev...