Crucial to medieval no-fantasy role-playing game Kingdom Come: Deliverance is its first-person melee system, which the developer has hailed as "revolutionary".
A bold claim, which is why this videoed demonstration is perhaps the most important video released for the game so far.
"We want the combat to be special," stated lead systems designer Viktor Bocan in it. "You will not kill dozens and dozens of enemies; every fight is unique and more like a duel than some hack-and-slash action game."
And, he said, restating the game's motto: "Realism is priority number-one."
Stamina will be vital, because you'll often face armoured opponents, "and to harm the guy in full plate is no easy task". But when your enemy tires you can swing more recklessly and with more power, eventually overcoming him.
Or, if you have the reflexes, you can expose weak points and kill much more quickly. This is demonstrated when an opponent is taken unawares by the point of a longsword in his face.
When you attack you choose whether to slice, slash or perform a special attack, which could be a kick or a punch or pommel strike. Then there are six zones on the enemy that you can target, totalling a possible 18 basic attacks.
There's a defence button that, if held down, automatically blocks attacks from all angles. But if you can time it correctly, you can parry, opening your opponent to a counter-attack. You can also feint an attack from one side but attack from the other, wrong-footing your opponent and landing your blow unimpeded.
That, by the way, is just the longsword - in the full game there will be an entire arsenal at your disposal, each weapon with its own situational strength.
You can face multiple opponents, by the way, but it will be "very complicated", Bocan warned. "You will have some special skills for fighting against more enemies, but usually it's much better to bring some allies and fight as a group."
Larger, pitched battles are a promised attraction in Kingdom Come: Deliverance, and there's an unsettling clip of two armies, 100 meters apart, preparing for the charge.
It's unsettling because you're watching it one row from the front, surrounded by a sea of soldiers just like you, facing an army just as vast. It hammers home just how insignificant one footsoldier was in a battle that big, and just how unlikely they were to survive.
That's the effect Warhorse is going for, and your orders at a moment like that will be simply to survive what comes next.
There will be castle sieges, too, and while you may have some say in larger strategical decisions, you'll otherwise be scaling walls on ladders or defending those walls from the attackers, be it with bow, sword or boiling oil.
But, remember, this is a role-playing game, so there will be some dramatic licence taken to ensure you become the hero of this tale.
"Don't worry," said Bocan, "Deliverance is still an RPG game; it's not only you who's fighting but also your character, and your character has skills and perks and abilities, so when the enemy is too strong for you, you can just slow down a little bit and level up. You may find some famous trainer and train with him; you can read a book about fencing; you can just level up by fulfilling some other quests, and then your character is stronger."
You won't just hit harder: if your sword skill is higher you'll be faster than your opponent and the fight will feel much easier. Or you could simply whip out a bow and shoot an enemy in the face, which the demonstrator recreates expertly during the clip.
Kingdom Come: Deliverance took to Kickstarter to prove to a private investor that there was an audience for this kind of game. If successful, the investor would stump up the millions needed to create the PC - and hopefully PS4 and Xbox One - game.
The Kickstarter target was Ł300,000 and Kingdom Come: Deliverance easily reached it. With nine days to go, the total is nearly Ł700,000.