I think currently, you can only set the chance of a tech appearing to be 1-100%. It would be fantastic to have the ability to set certain criteria (for example *and* statements, *or* statements, and *not* statements) for requirements for unlocking certain techs, if this is not in already. And you could make it so that if you have a particular tech (and/or other characteristics of your side), you cannot unlock another specific tech or tech branch. This would provide the ability for practically unlimited tech tree balance and customizability. 
Best regards,
Steven.
