"Early-modern" in this case is an eclectic mix of elements from late medieval to early 1600s. It also depends on the resources available to a given vassal - some will have trouble sustaining professional armies and rely more on levies and mercenaries, and others might have professional armies but no access to saltpeter for domestic gunpowder manufacturing.

In any case, I will PM you both the link. Take a look at it, read over the backstory and mechanics, and maybe dig into some of the past/ongoing events. Hopefully it will pique your interests.