I've always been a fan of games that, even if they have a traditional "dice roll to hit" or similar system, include options that avoid that randomness. Think attacks that deal less damage, but either always hit (my personal preference) or swap their die roll for a flat number. Sadly it seems like a lot of mainstream games in the vein of Pathfinder or of course DND are not inclined to include these sorts of mechanics - I personally suspect this is because they fear non-random outcomes (which is why virtually all of DHD's nonrandom spells like Knock or Magic Missile are just carry overs from the earliest versions of the game) though it could of course be a more calculated decision that I simply don't know the details of.
Regardless, it's cool to see that you implemented such a mechanic in your game! Well, assuming that changing the damage type is a useful option to reduce damage - but I'd assume that it is, if it's an option you bothered to provide.
Do enemies roll to dodge or parry attacks? If so, then it's not so much that attacks aren't decided by chance, but rather just that it's the GM making the roll rather than the players - an interesting especially as so many PBTA inspired games transfer rolls that are traditionally the GM's to make (think enemy to-hit rolls) to the players instead.
Are the rules available anywhere to read? I'd be very curious to look through them!