Beheading kings.

Trebuchets, which btw are far superior to catapults.

Strange women lying in ponds distributing swords as a basis for a system of government.

Royal beheadings

Our leaders fighting in the wars they start.

You wanted it... go fucking get it cowards.

Guillotines.

Inns, especially if they've got an enormous pot of perpetual stew, and people are giving out quests.

Peasant uprisings, to take down the kings of today.

Having most of the year off for festivals and holy days

Guillotines obviously.

My non-joke answer is apprenticeship. Kids could actually learn how to do a valuable job rather than graduating from high school with almost no useful skills.

Perpetual stew, good architecture, and no Twitter

The stockade is something we desperately need. Some people need to learn how other people see them. Driving 50mph in a living area, stockade. Making a lot of noise at 6 in the morning, believe it or not, stockade. Being a racist cunt, straight to the stockade.

I just really like walking around eating giant turkey legs.

Regicide.

Fucking castles, duh

Winter

Cloaks would be cool. I know that's more of a fantasy aesthetic than a medieval one but they are cool enough that it shouldn't matter.

I unplug for a few days and this pops up on my feed. ??????????

Child labor.

Oh, wait…

Dueling. I say we use it as an option to reply to a civil lawsuit. Able bodied adults only, no proxies, and if you refuse then you have to do a trial and they can weigh your refusal as evidence against you.

Swords only, no guns.

Catapults, just to irritate the trebuchet people.

Guillotines for kings

Weird ass slices in public parks everybody has to garden in. https://en.m.wikipedia.org/wiki/Open-field_system

Kings, plagues, private armies (more late medieval and renaissance, but you get the idea), career military with hi-tech weapons tearing apart barely armed peasants. Idk, OP, seems like we got almost everything covered

Syphilis

Cloaks and leather boots

Trebuchets - the superior siege engine. (Disclaimer: probably not medieval)

Royalty and nobility taking part in actual on-the-ground warfare. I'd be curious if that would have any effect on military operations...