Hi, greetings from Germany! :)
I've been reading the comments on this topic and then took a look at the presentation myself.
I'd like to start by praising the presentation; I'm sure a lot of work went into it, and there's a real eye for detail.
My only concern is that the demands this server places on the Metin2 community might not be met, or even be met, by most of us, the "OGs," as I like to call them, have all become "Boomers" and generally have very little time, patience, or energy left.
I think the server concept itself is respectable, ambitious, nostalgic, and inspiring.
Things like sprinting with the Shift-Key are a very clever idea and could definitely make sense in PvP.
A minor overhaul of the classes and the sophisticated systems is also nice.
BUT, and this is a big but, I think - and yes, I agree - I find it too "difficult" and too time-consuming and in the end thinking, perhaps it really is just a waste of time if you also see time = money. I understand that it's meant to be a long-term project, but when I played Metin2 back in the day and also from time to time especially on a P-Server, I eventually wanted BiS equipment so I could play PvP as well as have fun in PvE, of course. I don't think artificially recreating that "feeling" from back then won't really work, in my opinion, because it was simply a different time then. That doesn't mean a private server can't be a great memory, tho. There are plenty of examples where it was... Well, moving on I don't necessarily want to compare an Oldschool server to the days when Amboss fought JaYZoN just because we're talking about one xD but you know what I mean.
I've also picked out a few key points that might be worth considering.
First, the horse system. I'm not sure if I understood correctly, but do you have to wait 18 hours after each level?
Bonuses are another point that really stood out to me. For one bonus modifier, you need certain licenses that you can farm from Metins, bosses, etc., which is good in principle. However, I would simply remove certain low bonuses altogether instead of torturing players to finally get the right one to switch in for more efficient progress. A little bit more Quality of Life in general is the key. (like Max. HP of 2000 instead of 1500).
Permanent HP and MP potions to get started - nobody really wants to use potions, and some Dews need to be a just one size. Many servers, even before yours, initially handled it this way until they quickly realized that "Keep it Simple" is better for certain things. I'm sure I noticed more things, but I didn't want to write a novel :D As you can see, I'm also looking for "the" server or the next big MMO, but time will tell.
Oh, and one more thing: the mobile version you teased in the presentation looks very interesting. However, one thing immediately caught my eye. What about a second character or screen, for example, if you want to have a Buff (Shaman) character with you? Will these be available for purchase in the Item Shop, or perhaps like in Flyff Universe, i don't know if you're familiar with the game, but it offers something like a beginner buff up to level 30 at the central Map. Could something like that be considered?
I hope I haven't offended anyone with my brief feedback. All in all, I wish you all the best and the best output and input, and as a long-time Metin2 player, I'll definitely be checking it out at release. Have a good evening and good luck and success!