An old MMORPG (Although perhaps not so massive by today's standards) from 1995, which is still going, called Meridian 59. The most active server for the game is the relatively new open source server, which you can check out at
www.openmeridian.org.
First off, it's full loot on death, non consensual PVP, pretty harsh penalties for dying, so it sounds like it's up your alley.
Admittedly, the PVE is a bit grindy, although they just recently updated the monster AI, and it's apparently much better.
There aren't any character classes, you just allocate your stats at character creation, select a couple starting skills and/or spells, and you're off to the races. Spells and skills improve as you use them, HP improves as you kill enemies slowly over time, and getting good enough at the spells or skills unlocks the next level of them.
You can kill other players after you've advanced a little bit, killing someone else marks you as a murderer, meaning other people can then kill you without themselves becoming murderers. There's kind of a player killer/hunter dynamic, although with the somewhat low population the player killers are a bit more common.
It's had pretty much the same playerbase for 15 years, but new people do come and go from time to time. I recommend people try it out.