Friday, October 2, 2009

Rules of War: HELLAS (and D20) Edition!

A buddy of mine, one of the writers of HELLAS, asked about the rules I created for rpg mass combat. He wanted to give them a look, since some of my players were raving about them. After glancing at them, he said "This looks good. Is there a way you can convert it and make it more applicable for HELLAS?"

I naturally said "Sure!" and then immediately thought "Wait... How fuck do I do this?" It took a little crunching, but I managed to convert the die pool system I had originally used to a simple version of the Omni System that uses only a D20. I managed to keep all the flavor of the original rules and even incorporated a little of the panache that makes HELLAS so fun.

As a bonus, there's absolutely no reason the HELLAS version of The Rules of War won't drop smoothly into any other D20 based game out there! Enjoy...

The Rules of War - HELLAS Edition

Warfare Mechanics Inspired by Sun Tzu

When 550 soldiers attack 1000 farmers, most game systems break down. These rules handle large battles quickly, with just enough strategy and drama to maximize the fun, while the PCs get a chance to influence the battle around them!


The larger army always starts at Size 10. Divide the number of troops in the larger force by 10 to determine the worth of each point of Size and then give the smaller force a proportionate Size (round up). This represents quantity alone, quality is factored later. Size, for both armies, may be doubled for longer (i.e. more dramatic) battles.

Example: If 1000 farmers are Size 10, then 550 soldiers are Size 6.


There are six fundamental factors to determining the outcome of a battle. Superiority in all six of these factors all but guarantees victory. Therefore, advantage in any factor grants an army 1 Strength. Determine which army possesses the advantage in a coming battle by answering the following questions:

  1. Psyche – Which army possesses the highest morale?
  2. Heaven – Which army benefits most from the weather, time of day, etc?
  3. Earth – Which army gains more advantage from the terrain?
  4. Leadership – Which of the two generals is the better leader?
  5. Discipline – Which army is more skilled, trained, and supported?
  6. Spear – Which army uses the best weapons and technology?

No significant edge, grants no bonus for that category. Clear advantage grants 1 Strength.

Example: The soldiers have high morale, good leadership, great discipline, and good weapons, giving them 4 Strength. The farmers gain advantage only from their home terrain, leaving them with only 1 Strength. The sky, cloudless and clear, grants no advantage and no bonus to either side.


To do battle, each side will implement a simple strategy to apply its Strength most effectively against the enemy’s Size. Each round of battle consists of the following phases:

1. Strategy – Armies choose how much Strength to apply to defense and how much to offense

2. Chaos – A D20 is rolled for each army, with the Degree of Difficulty determined by the following:

a. Strength applied to offense adds a +2 bonus to the rolling army’s DOD

b. Strength applied to defense adds a -2 penalty to the opposing army’s DOD

3. Reckoning – Compare the final roll, after modifiers, to the Omni Table as usual:

0 or Less Critical Failure Lower the rolling army’s Size by 1

1–5 Failure No damage is inflicted to the opposing army

6–10 Partial Success Lower the opposing army’s Size by 1

11–19 Success Lower the opposing army’s Size by 2

20 or More Critical Success Lower the opposing army’s Size by 3

Example: The soldiers apply all their Strength to defense ( -8 to the farmers’ DOD) and the farmers apply theirs to offense (+2 to their own DOD). A D20 is rolled for each army, the soldiers have a 15 and the farmers have a 16. After factoring in Strength, the soldiers remain at 15, but the farmers are dropped to 10 (16 rolled, +2, -8). The soldiers lose only 1 Size while the farmers lose 2. The farmers fought surprisingly well that round (rolling a 16), but still lost many men.

Spotlight Missions

After each round of battle, PCs can volunteer for spotlight missions in an attempt to affect the factors contributing to the opponent’s Strength or their own. Many PCs can volunteer for the same mission, thus fighting together and increasing the chance of success, or separate to take on several missions. Missions can be anything the PCs dream up, scouting, assassination, demolition, etc. It’s up to the GM to determine the difficulty and opposition for each mission, but they are under no obligation to make a tough assassination attempt easier should only a single PC undertake it.

Note: Only PCs not directly contributing to Strength can undertake spotlight missions. A PC acting as the general of his army, thus contributing Strength through Leadership, cannot step down for a secret scouting mission without forfeiting his contribution to Leadership as well.

Missions are resolved using the normal rules for HELLAS. A spotlight mission can be detailed and drawn out to add drama or shortened and summarized to speed the action. Ultimately, each spotlight mission should produce an opposed action to gain, or maintain, the advantage. After the roll, the Strength point for that factor goes to the winner.

Example: Two farmers attempt to break the soldiers’ morale by undertaking a spotlight mission. They decide to defeat a group of 10 soldiers in a spectacularly bloody fashion, loudly proclaim themselves to be “The Chosen Warriors of the Right Hand of Areson”, thus sowing fear and uncertainty among the opposing ranks. Should they succeed in defeating those 10 soldiers, they’ll need a Deception roll vs. the soldiers’ or their general’s Deduce Motive as he attempts to rein in his men. The Degree of Difficulty for that Deception roll can, and should, be modified if they defeat more or less than 10 soldiers.

Players should be encouraged to get very creative with ideas for spotlight missions, but GMs should step in with any ideas or alterations of their own. If a PC wants to call forth Hephaeston to melt enemy swords, the GM should help out by declaring the number of swords necessary to make a difference.

Additionally, PCs may opt to protect the Strength of their own army rather than weaken their opposition. An army that already possesses superior Leadership has no need to undermine their enemies. Instead the PCs could simply guard their own leaders to make sure no terrible fate comes to them. This is, of course, an opportunity for the GM to send assassins their way. Treat it just like a spotlight mission being undertaken by the opposing forces!


An army is defeated when its Size is reduced to zero. Whether this defeat is due to destruction, rout, or retreat simply depends on the narration up to that point. After the battle, each army attempts to recover its losses by healing the wounded or tracking the fleeing. This is done by rolling a D20 for each army, applying a Degree of Difficulty of -5 (loser) or a +5 (winner), and checking the result against the Omni Table:

0 or Less Critical Failure Army loses an additional Size from disease, injuries, etc

1–5 Failure Army recovers none of the Size lost

6–10 Partial Success Army recovers only 1 point of Size lost

11–19 Success Army recovers half (rounded down) of all Size lost

20 or More Critical Success Army recovers all Size lost

The GM is encouraged to modify the DOD on the casualty roll during unusual battles. The Atlantean habit of devouring dead opponents would make recovery for difficult for the opposing armies. Alternatively, Priestesses of Hestia will have an unusual knack for recovering their own fallen warriors.