Sunday, 20 May 2012

1d10 design mistakes in DnD 4e - Tactical movement

Tactical movement speed in DnD is typically in the range of 5 to 7 points per turn. There is no facing and therefore no turning cost. Most squares cost 1 point to enter, with difficult terrain doubling the cost to 2 per square.

The commonly used movement actions are walk (base speed), run (speed + 2) and charge.

You may want to read that again.

Walking is a gait where one foot is always in contact with the ground. Typical walking speeds are around 5 kilometres per hour. By contrast, running humans have a top speed (world record) of 44.72 km/h. That is nine times faster than walking!

This is of course over a short distance and without being encumbered, but even cutting it to a more reasonable 20 km/h would mean running is four times faster than walking. However in game terms, a speed 6 human runs at speed 8, a mere 33% increase. This is painfully gamist for anybody who bothers to engage his brain for a moment to consider the design choices made.

Walking in DnD
Running as fast as you can in DnD

Arguments that this is based on the action split between move and combat activity (such as parrying or attacking) will fail to convince as the same 33% increase applies when doing nothing but moving. Double move at walk speed would achieve a speed of 12, while a double move at run speed would reach 16 speed - this is the same 33% difference.

This can be contrasted with the design in a simulationist game, where the fastest movement speed is five times the base walking speed. A character moving at 15 metres per round (50 feet) at walk speed can dash 75 metres per round (250 feet). This is a far closer match to reality and thus much more believable and the difference is obvious in the illustrations below.

Walking in a simulationist game
Dash in a simulationist game
 More after the break.

I mentioned earlier that the base movement types are walk, run and charge. Charge is described in the DnD rules as follows:

You throw yourself into the fight, dashing forward and launching an attack.

Dashing forward sounds like a burst of speed and might bring to mind something similar to the 5x pace in the simulationist game. However this is completely misleading as in fact a DnD charge action involves moving at normal walking speed. In fact, if you run at the enemy you suffer a -5 penalty to hit. This is summarised in the following table (using base speed of 6).


Note: N/A entries means you are forbidden from making an attack. The defence modifier of -2 is actually implemented in the game as Combat Advantage (+2 for enemies to hit you) and has implications relating to various class features, feats and magic items.

The table shows that players have a number of interesting choices such as:
  • Move 6 squares and attack or move 6 squares and attack with +1 to hit.
  • Move 8 squares and attack with  -5 to hit.
  • Move 12 squares and not be allowed to attack or move 12 squares and attack with +1 to hit.
  • Move 14 squares and attack with a -4 to hit or move 16 squares and not be allowed to attack.
What should really stand out here is the complete inconsistency. Depending on action combinations you get an utterly confusing range of outcomes. Any rational design for a world governed by Newtonian physics would instead be based on a sliding scale derived from speed of movement with a multiplier based on creature size to account for mass.

Finally I'll point out that as the table shows running makes combatants an easier target for missile attacks as they immediately grant combat advantage to all other combatants. Forget any ideas you might have about quick moving targets being harder to hit - in DnD the tough targets are stationary, if they run you get a 10% bonus to hit! Again inconsistency is rampant as you can walk 12 squares in the same fixed time as somebody running only 8 squares, with no modifier for hitting the walking target that actually covered more ground than the runner.

A further criticism of DnD in this area is that plate armour (the heaviest armour in the game) reduces speed only by one point and does not affect the ability to run. Thus we are asked to believe that a human would only lose 1/8th (12.5%) of his running ability when wearing this:

Picture by Perfect Zero, used under Creative Commons license
In more reasonable systems, heavy armor would prevent moving at very high speeds and there is a far greater distinction between unencumbered runners and those in armour. This creates a realistic trade-off between protection and speed.

Finally I will highlight how DnD handles running away. Consider the situation where a foe breaks and runs from melee, perhaps due to having seen his companions defeated. With a base speed of 6, deciding to run (speed +2) and do a double move by substituting his standard action for another move action will get him 16 squares in a single turn. Because he started adjacent in melee the enemy gets a parting strike (Attack of Opportunity) against him with +2 to hit (running grants combat advantage).

If the enemy has a movement speed of 5 or less, the runner will get away free. Nobody can catch up with him as at best they would double move run for 2 x 7 = 14 squares. However, if they have a move speed of 6 they can pursue and immediately catch up by running a matching 16 squares.

As the next turn starts the situation repeats, ad infinitum and ad nauseam until the runner succumbs to the blows from behind. There is simply no getting away and the enemy will keep getting free attacks every turn while the fleeing combatant is unable to attack at all. With no rules for exhaustion both parties can run indefinitely.

It should also be noted that a pursuit can not be ended by attempting a Grab action as it is necessary for the pursuer to use double run to keep up with the pursued. Thus it is impossible to make a grab for the enemy despite being close enough to swing a melee weapon as an Attack of Opportunity.

This has two important outcomes for the DnD systems. First, it renders the act of fleeing useless unless you have a speed advantage or somebody is covering your escape. Second, it removes all potential for excitement from a pursuit situation. The act of chasing is reduced to a comparison of base speeds without any consideration of potential tactics.

A better design would have explicitly considered:
  • Greater variation in pace (1x through 5x instead of 1 x through 1.33x), with real benefits for those who drop their weapons, shield and armour to reduce encumbrance.
  • Trickery such as feinting a move in one direction and then breaking away in the opposite direction, governed by the Bluff skill.
  • Attempting to gain distance by increasing speed beyond normal limits, governed by the Athletics skill. Success would allow additional squares of movement. Fumbles would indicate a potential trip, with a Reflex save to stay on your feet.
  • Imposing limits on running by enforcing Endurance skill checks with escalating penalties after consecutive run actions, with failures forcing a reduced speed. Fortitude checks could be used to regain your breath and remove the stacked penalties every time you took a 'rest' action instead of running.
  • Tripping or tackling the opponent through the Acrobatics and Athletics skills.
Hopefully good DMs will develop house rules for this, but it is regrettable that the rules failed to cover the rules of pursuit. More integrated skill use in combat would also benefit the system, for example using Bluff to feint and break away to negate Attacks of Opportunity should really be part of the standard toolkit for any Rogue or Ranger.

4 comments:

  1. I think of both the standard move speed and "running" move speed as running. The only difference I see is that you grant combat advantage in the other.

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  2. You are spot on and I think your suggestions on improving the system are very reasonable. Thanks for the insight.

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  3. I agree that running should get you at least double your move speed (at the cost of granting combat advantage). In combat, though, I think of an encumbered (gear, weapons) fighter who is 'running' to really be doing more of a jog, which is hardly the sprinting speed an unencumbered runner. I like your idea of dropping gear to run faster...seems like a good house rule would be that run speed is a formula involving your base speed and your current load relative to your max load. For instance, a smart fighter would probably drop his heavy backpack before engaging some enemies in a fight to the death.

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  4. Your analysis of movement speed neglects the presence of action points (1 AP after extended rest, +1 AP after every 2 encounters, some monsters also have APs), which could potentially be expended for an additional move action (24 squares running the whole way), as well as minor actions (a number of classes can gain access to movement powers which expend minor actions). In your "chase" scenario, you ignore the use of ranged attacks. In particular: attacks which slow, teleport, force movement, or reduce/remove the runner's ability to take actions, as well as the creation of friendly (affects only enemies) difficult and/or blocking terrain. Some characters can even gain the ability to simply say "no, you DON'T escape," such as a pursuit Avenger, who has powers along the lines of "if the target ends its turn more then 3 squares away from you, teleport to a square 3 squares away from the target as a free action."

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