My DM once gave me a cursed sword that required me to kill a humanoid daily.
It then devolved into side bars where we had to negotiate taking a kingdom's prisoners with us in the hold of a boat on our mission to save the queen or whatever. For murder sword food.
Still one of my favorite campaigns. I do think he regretted giving me an excuse to derail his campaign to go murder-hoboing, though.
That's actually a really great introduction to D&D! It's basically the same thing, except the voice actors are terrible IRL, and the graphics take place in the theater of the mind. But you have a lot more freedom to be creative and veer off track, which can be amazing.
Or discussing the scientific implications of magic. That happened way too often. I'm pretty sure that one specific DM will never give anyone an Everfull Stein ever again.
Your #1 challenge and task as a DM is to stay ahead of the players.
Fighting everyone you meet? Guess what you're in a survival adventure now hiding in the hills because the whole king's guard is scouring the hills trying to TPK the party after they killed the shopkeep.
OH I BET YOU'D LIKE TO BE ABLE TO GO TO THE SHOP, WOULD YOU NOT
It's okay, there is an orcish caravan coming through. They want to fight you, but maybe with some skillful rolls you can talk them into doing a little trading through the 1-2 of them that speak common, at least get some food and heal potions and crossbow bolts. You can get kitted out at least well enough to make it a few weeks' journey in any direction and hope the heat dies down before you all get killed.
OH YOU FOUND A DUNGEON ON THE WAY, LET'S DO SOME FUCKIN FIGHTING
WHAT DO YOU MEAN YOU DON'T WANT TO GO IN THE DUNGEON, I THOUGHT YOU LOOOOOVED FIGHTING YOU FUCKIN COMPULSIVE FIGHTING PEOPLE
Guarantee when they get to the next continent for their fresh start (if they make it without the TPK) they will be more amenable to being nice to the NPCs. Or, maybe not, maybe they will have enjoyed the whole process and we get to do the whole thing again, which is also fine and also pretty funny tbh.
To be clear, I don't kill anyone. I only beat them until they will never recover enough to seek vengeance.
We can make it funnier. I have a resurrection artifact that is cursed, every time I am killed and get resurrected I age 5 years, but beating a human in unarmed combat makes me one year younger. There is no dying of old age, I keep coming back older. So either I am a feisty frail old man or I end up a kid that people have to kill because I don't stop attacking until my 20s.
Then you have the opposite end of the spectrum where my Wizard and the party Rogue were accidentally competing with each other as to who spoke more languages. My wizard won that battle by hitting 21st level first and taking Polyglot as her first epic feat.
We managed to negotiate a peace treaty with the local orcs, and even got them to send an army to help us deal with a much bigger problem.