2.2+ Design Notes: Measurement and Scale

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30"/48" standard board size

48" boards have always been in use for 25mm scale DBA, despite being removed from the 2.2 rules. 2.2+ just makes the commonly used board scale for 25mm games official.

30" boards have been in common use in many geographical areas for 15mm scale games, and are widely regarded as providing a better game with more room to maneuver around the enemy's flanks. This change has been widely tested over the course of hundreds of games, and there are no real downsides to using this board size. The larger board makes it possible to avoid the "end of the world" effect if you want to, and any meaningful movement restrictions are handled very effectively by the general's command radius limitations. It is also closely proportional to the 48" standard board for the 60mm wide bases of 25mm figures which has worked quite well since DBA 1.0. A 32" board for 40mm wide bases would be exactly proportional, but structurally inconvenient to use on the common 30" wide tables found in many convention centers.

Why not support multiple board sizes in the rules?

Opponents or tournament organizers who agree to use a different board size are welcome to do so. This is what has been done for years with 30"/48" boards in areas where they are used.

However, the rules must declare what should be done when players don't agree on what board size to use. This requires either a rule to determine which board size to use every time there's a conflict, or more simply, a single standard board size. It was decided that supporting a single board size is the simplest way to solve this, and all of the designers prefer to play on the 30"/48" board size.

MU movement units

Changing movement units to be based on the base width instead of the arbitrary "inches" it used to be provides several benefits.

  • Avoiding peculiar mixes of measurement systems. Inches and cm in the same rule system is odd.
  • Lateral movement down a line suddenly makes sense. No more moving 76.2mm sideways to fit a gap, ending up 3.8mm short of being able to block a hole two base widths over.
  • Some minor reduction in the rules (closing the door rule no longer needed)
  • Scale independence – 25mm scale would play the same as 15mm scale
  • Little or no significant change in comparative movement rates from v2.2
  • Creation of a new slot for movement rates that can be used to support some type regrading or new element types (for example, Cataphracts can now be slower than Knights, and Raiders/3Sp can be faster than Blade/4Sp, yet still not as fast as Auxilia or Psiloi)
  • Combat outcomes and tactical moves tend to coincide more closely
  • Gameplay is overall much smoother, and less measurement is required during play

Movement rates based on a fraction of a base width have merit independent of the specific movement rate categories chosen.

Why "MU"? Why not use "base widths"?

Setting the smallest increment of movement distance to of half a base width instead of a full base width is preferred to allow more different movement rate categories. Measuring things in base widths and using fractions of base widths in the basic measurement is certainly possible, but it isn't as convenient as measuring everything in whole units. The term "HBW" or "half basewidth" was used until MU or "movement unit" was settled on as a better alternative.

Movement distances

Some of the ratios between various distances in the game are more important than others. The 2.2+ designers identified which of these ratios are more important, and have attempted to ensure that these ratios are maintained appropriately in 2.2+. The less important distance ratios aren't as important to maintain, and may have changed in 2.2+ as a result of other more important changes.

Here, "movement rate" is used to mean "an element's maximum movement distance."

More important distance ratios

  • The ratio between an element's base width and its movement rate
  • The ratio between an element's base width and the size of the board
  • The ratio between an element's movement rate and the size of a Zone of Control
  • The ratio between movement rates and shooting ranges
  • The ratio between movement rates and command radius

These distance ratios affect an element's ability to maneuver locally, and affect how much space the army takes on the board compared to the amount of space available to use around the flanks of the army.

The specific movement rates chosen define how much action can be taken before an enemy has a chance to respond to that action.

Less important distance ratios

  • The ratio between movement rates and the size of the board
  • The ratio between different elements' movement rates

Increasing or decreasing the overall ratio of movement rates versus the size of the board speeds up or slows down the game, but it's more important to properly limit what maneuvering can be done in a single turn.

Difference between movement distances

The 5 different movement distance categories are more important when the change is made in conjunction with other changes such as "you can only break off from combat if you're faster."

However, these different movement rates have different implications to element maneuverability independent of any other changes. Here is a chart David Kuijt produced to explain the difference between different movement rates, with respect to closing the door on an element in the enemy's line.

For two lines in combat, one overlapped (the element in question being the overlapping one), using front corner measurement and Pythagoras, we get the following:

  • 3MU move: can close the door on an element that is a smidge (4.7mm) apart from the main line
  • 4MU move: can close the door on an element that has recoiled or is otherwise back 29mm from the main line
  • 5MU move: can close the door on an element that has recoiled or is otherwise back 51mm from the main line -- so any recoiled element, but not an element defensively covering the flank with ZOC
  • 6MU move: can close the door on an element that is 73mm back from the main line -- a ZOC will still protect.
  • 8MU move: one refused element won't do the job.

In other words:

  • A Spear can close the door on an element it's overlapping, but not if the enemy element recoiled in a previous combat. No rule exceptions are required to allow this.
  • A Raider can close the door on an enemy element with a 15-20mm base that recoiled once, but not against mounted.
  • A Knight or Cavalry can close the door on any recoiled enemy element, but the enemy flank can be protected by another element exerting a ZoC without the protecting element being in danger of contact.
  • Light horse can always either close the door on an element, or contact an element that is trying to protect its flank with ZoC.

Ground, figure, and time scale

The 2.2+ designers have made a conscious decision to reject all ground, figure, and time scales that were defined in the DBA 2.2 rules. This means that no argument based on real life time, ground, or figure scales will be considered a valid reason to make or reject a proposed change to the rules. For this reason, there are no "paces" defined in 2.2+.

The primary design priority for 2.2+ is to support armies of widely different sizes across a long period of time to fight each other using a standard 12 elements independent of the size of the historical army. The consequence of this design decision is that the size of an element in real life varies very widely from one army to another. Any attempt to maintain a consistent ground scale is doomed by this primary design priority.

Therefore, it is better to dispense with the specific real life scales, and instead focus on how troops were used. The rules should encourage historically accurate use of different troop types, and should allow for historically accurate results to occur when they reach combat. In the end, die rolls decide what really happens; but that's true of history as well. We will never know how many 6-1's Alexander the Great rolled during his major campaigns.

With this in mind: movement rates and distance ratios have been chosen to encourage historical behavior and produce historical results at a high level of abstraction. They have not been chosen to accurately represent time, distance, or man to figure ratios to any fixed real life scale.


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