The point of combat
My goals when designing a combat system are that it should first have enough dynamism to not be a solved game or rote repetition, second be as simple as possible, and third be as realistic as it can. The order there is very important. I do not want to play a tabletop RPG that is mostly or entirely about combat, that's something I find video games will always have the advantage at, in terms of providing an exciting, tense experience. So here are three of my favorite attempts I've made at creating the kind of combat I'd want to play.
|Duel by Antonio J Manzanedo|
Three Hand Duel
There are three combat stances: fast stance, parry stance, and feint stance. Parry beats fast, feint beats parry, and fast beats feint. Anyone can use fast stance, anyone with a weapon (or specialized unarmed training) can use parry stance, and anyone proficient with their weapon can use feint stance. Anyone whose stance beats opponents’ stances deals damage dice plus bonus damage. Anyone whose stances matches their opponent's both deals and takes bonus damage (but not damage dice). Blocking stance is available if you have a shield, allowing you to roll a 'damage die' that will reduce any damage you take in the following round. Weapons and high strength increase damage, armor reduces damage taken.
Advantages: pretty complex without being hard to use, gives plenty of active decision making opportunity to players. Inherently feels flavorful because you're declaring how your character will fight. Easily scalable up to mass combat with something like charge, flank, route or similar (I haven't looked into medieval battle strategy). It also addresses the massive threat of being flanked, as both opponents can doom your options. There is also some opportunity to add special stances as class abilities or other kinds of specialized combat training, but this should be done with extreme care. Also runs faster than most dice systems, because someone is always taking damage.
Challenges: make sure you choose what your stance will be before you ask someone, you'll probably want to write it down. Honestly cards might work for this purpose. Also a bit hard for people to wrap their head around if they're not familiar with the terms, but they can be easily equated to rock, paper, and scissors (obviously what the system is based on). Also if you're unarmed or not proficient, there's always a best choice against you, so that's iffy.
|Battle by Faraz Shanyar|
Behind the Blades
Each character has a stamina stat. Before the turn, they can invest however many they want into offense and defense respectively. If one side's offense totals higher than the other's defense, that amount of damage is dealt. Armor and shields add fixed defense points, weapons and strength add fixed offense points. Possible additional rule: one may invest a third of their stamina in a 'guard break' that reduces enemy defense to zero. Stamina may lower each turn.
Advantages: very simple, very deadly. Again, possible to add special moves with a fixed stamina cost, or a fixed portion cost.
Challenges: again relies heavily on not knowing what the opponent will do. Even more so, knowing the enemy's stamina can potentially cause problems.
|Spilled Wine by Daniel Landerman (NSFW warning)|
An attack is a d20 roll. If the result is higher than the opponent's defense, the attack is successful, and you can either strike them or shove them away. The first strike throws you off guard for a turn. If struck while off guard, you are wounded and unable to fight until healed. Strikes can be either deflected or absorbed, with a weapon or tool you are holding. Deflecting causes you to drop that item, while absorbing the strike damages the item. It takes one turn to attack, close distance (such as after being shoved), run away, grab two items from the ground or your belt, or grab one item from a container within reach (like your backpack) or from another belt in reach. Armor and shields add to defense, weapons and combat training add to attack.
Advantages: most compatible with D&D style combat systems, which includes a lot of OSR stuff, so conversion of existing combat should be a lot easier. Lots of potential for environmental fun, like shoving people into hazards (down stairs, into spiders) or dropping a weapon out of reach (off a bridge, down a cliff).
Challenges: the way shoving and running away work, there should probably be a similarly robust chase system. That seems like fun, but it is a challenge. Should also come with somewhat strict limits on what can be hung from a belt, lest players simply load their waist with spare weapons and shields.
If you've been following for a while, the Three Hand Duel was what I was using for my Skies Below stuff. These are still broadly in chronological order, in the order I came up with them. I'll probably stick with Steel Ruckus for the time being, and flesh it out with more details in the future.