Thanks to
@Nagash I noticed that there is no love for undead fans. The only exceptions being skins and I really hope you understand why skins are a horrible solution for skeletal loving players

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I do understand that giving the option to create an undead from character creation from scratch may collide with IS vision of the lore and feel of the game, but I think I have a solution that can either be done in a lazy way or a deep way. Both are effective and will evolve the game for atleast a minority of the player base while not ruining the experience or lore for others.
Enter: "Insert edgy undead clan/guild name"
When you start the game you choose one of the regular races. From my understanding the game offers different NPC guilds, clans and groups for you to explore content with.
What you could do is create an undead clan. Once you progress enough in this clan, either by grinding, or following a story or doing specific tasks you will be given the choice to become one of them. They will then tranfsorm your current race through a ritual to become an undead version of your desired race.
The lazy way
The undead ritual only changes your visuals. It gives no abilities or gameplay differences. In this way, you will please a group of players that love to play as undeads while not affecting the game in any way except for the better. It is up to you intrepid to design the lore about this in a way you like.
The deep way
Races that go through with the ritual change the very nature of their being. A Ren'kai, that usually has difficulties controlling their rage and having acces to abilities that increase damage with the weakness being more damage taken will no longer have this ability.
Instead, all races that become undead are unified under the same "special ability" group. This could for example be infinite underwater breath, resistance to poison or whatever you name it.
Summary
To please the undead race fanbase, offer a way to turn our races to undead versions of that race. Either only visualy, or with special abilities unique for undead.