Cool video that you’ve put a lot of thought into. I think the underlying concepts and reasoning you’re going for it great and you’ve outlined almost an entire progression system. I feel like you could design an entire passive system around stat milestones. I think D4 would do well to use it.
I know a lot of it is directed at D4. I think we’re doing most of the things that you are suggesting as important things to do. Player choice in gear with trade-offs being the catalyst for interesting decisions. Build customization through skills and character building. The milestones system is actually really good at doing something that we’re struggling a little bit with gear. It puts a “tax” on gear. It forces you to equip a minimum number of rare items. Certain slots will have uniques and sets but you’ll require a minimum number of rares to hit your breakpoints. Games like PoE and D2 do this with resistances by making getting res capped almost mandatory. As you mentioned, that’s not overly exciting and with the way our protections work and there not being a cap, it’s a little hard to use them like that. We have experimented with a couple systems to fill this role and currently, that’s what glancing blow is doing. It is something that our community has voiced as a low point in the overall design and we are working on an alternative. I think that the affinity and milestone systems are too deep for us to use without removing our passive tree. We are really happy with how the other progression systems are shaping up so we probably won’t adopt it wholesale.
Had this been pitched 2 years ago, we probably would have much more heavily considered it though.
Side note: We actually tested out how move speed acceleration feels in game and it’s terrible. Like really terrible. I thought it would be super cool and an interesting stat but all it ended up doing was making movement feel terrible until you had a ton of acceleration then it began to feel ok again. It made the first 50+ levels of the game just awful. I wish I was wrong on this one because you are right about it being more realistic.