RTS Game-play Part 6: Visible Balancing

December 9th, 2008, RTS Design

jeb <3 RTSMaybe it’s time for me to continue on this blog series, so here it goes… Got some interesting feedback on the previous posts, which is great! I really need to hear some criticism, so I know in which direction to take the completed article in. I’m going on vacation next week and wont be back until next year, but I’ll try to post as much as possible until then (though I doubt I’ll have time to write everything).

In any case, as I wrote in the previous post there are two main kinds of unit balancing, visible and hidden balancing. (I will alternately use the terms “concrete” and “abstract” balancing as well.) In this post I’m going to describe in more detail what visible balancing is, and give some examples. It’s worth mentioning that a lot of these suggestions aren’t restricted to RTS games only, but to game design and balancing in general.

Visible Balancing

Visible balancing is when the game’s mechanics prevents something from happening. For example, units that are unable to attack flying targets have been balanced using visible balancing. Visible balancing is easier for players to understand and learn than abstract balancing, but abstract balancing is usually required in order to maintain complete balance.

Another way of explaining the difference between visible and hidden balancing is that visible balancing gives explicit feedback while hidden balancing gives implicit feedback. Implicit is when you send in a group of soldiers in a melee and come out victoriously with half of the soldiers still alive. Explicit is when you send the same group of soldiers against a group of crossbowmen and have all of them shot down before they even get within reach.

A game should attempt to use visible balancing whenever possible.

Unit “Dimension”

“Dimension” refers to the units’ “plane of existence” and not unit size. For example, units that are walking on the ground are in one dimension (the ground dimension) and units which are flying are in another (the air dimension). Unit dimension is not the same thing as unit detection, which is described below. For example, in Warcraft 2 there are submarines that the opponent needs to detect in order to attack (using fliers or guard towers), but they still exist in the “ground” dimension (units which can attack ground targets can also attack submarines).

The number of dimensions in a game depends on the game’s setting, but can be tweaked by the game designer if necessary. Supreme Commander has three dimensions (air, ground and submerged), while the before-mentioned Warcraft 2 keeps it to two. Some games, such as Homeworld (Relic Entertainment, 1999) and Dawn of War have a single one.

Using dimensions is a very good way of adding concrete balancing to a game. They are usually easy to understand and easy to adapt to. They also make the tech tree more flexible and gives the game designer more options to explore.

Units that are able to attack units on multiple dimensions, or even cross dimensions themselves, are more valuable than other units. These are “versatile” units, and usually cost more than single-dimension units because they are harder to counter. Versatile units are sometimes balanced to be vulnerable to units that are specialized on attacking their dimension. For example, the Protoss Dragoon in Starcraft stand little chance against Zerglings, considering that they are about five times more expensive.

Attack Abilities

Attack abilities are things such as attack rate, range, projectile speed, area of effect and so on. These are visible ways of balancing attacks. Hidden ways of balancing is when using attack modifiers, such as damage and armor types. I will cover these in the next blog post.

Attack Ability – Rate

Attack rate, or rate of fire, is one attack ability which is easy to visualize. The rate of fire is controlled by a delay timer between attacks, and this delay can be placed before or after the attack, or distributed on both before and after. If the delay is placed before the attack, it will make the unit weaker compared to if the delay was placed after. This is because short reaction time will give the enemy units less time to move out of the way or shoot back.

The delay length will obviously control how quickly the unit is able to attack. In case you want to maintain the same “damage per second” ratio, short delays will make the unit weaker than longer delays. For example, imagine that a unit should deal 1000 points of damage over a second. If the delay is 0.2 seconds the unit would fire five shots that deal 200 damage each, and if the delay is a whole second, the unit would fire a single shot dealing 1000 damage. One big shot will give the enemy unit less reaction time and decrease its chance to get out of the fight alive. However, short attack delays are better against many weak units, so this type of balancing is useful if you want units to be good at different kinds of combat scenarios.

Attack Ability – Range

The attack range is  another visible type of balancing, since it’s quite clear to the player why a unit is able to attack or not. Attack range is a surprisingly strong unit balance modifier, because a unit with a range advantage will be able to deal damage without getting hurt at all.

Attack Ability – Projectile Speed

Projectile speed could also be called “the delay from attack until damage,” and is also clearly visible to the players. It’s not such as strong balancing modifier as attack range or rate, but having a quick projectile is better than a slow one. Slower projectiles can also create situations where units “waste” attacks on targets which are defeated while the projectile is still travelling.

Projectile speed has more impact in games where attacks are made on a position rather than a unit. Attacking positions makes sense, but will make balancing slightly more difficult since movement speed and micromanagement of units have more effect. For example, the Grenadiers in C&C 3 throw slow-moving grenades that aren’t homing, which means that if you pay attention you are able to move your units out of the way before impact. All attacks in Starcraft are homing (targets a unit instead of a position), which may feel unrealistic and inappropriate for your game.

Attack Ability – Accuracy

Projectile accuracy is another attack ability which can be both concrete or abstract depending on how the game presents it. Accuracy of archers in Age of Empires 2 is clearly concrete, because if an arrow hits a target it also deals damage. This is cleverly included in the game’s tech tree, as ranged attacks can be upgraded to aim in front of moving targets, increasing the accuracy in a visible way. Accuracy in Dawn of War, however, is implemented in an abstract way. Hit or miss is determined with secret dice rolls that are affected by a number of modifiers. This randomness is fine, but the problem is that visually it’s hard to tell if a shot has hit or missed. Additionally most weapons have a quite high rate of fire, which means that over time the accuracy is more or less a damage modifier rather than interesting gameplay.

Movement Abilities

Unit movement is also quite visible and can be used to balance units against each other. The most basic way of doing that is simply to change the unit’s movement speed (a very strong modifier), but you can also balance units by changing if they are allowed to move and attack, if they must turn and face the direction they are moving (turning speed), if they can pass obstacles (flyers) and so on.

Movement abilities are usually strongly attached to the look and feel of the unit, so maybe you’d rather prefer to fix the unit’s movement and then use other variables to balance it in global scope. As comparison, I haven’t heard of any games that has released patches which changed the movement style of units, but unit costs and damage values tend to hop up and down.

Cloaking and Detection

The title is somewhat mis-leading, because this ability is more about situation-based unit invincibility. These kinds of abilities are usually quite clear and visible to the players, but how they are countered can be a bigger problem. In other words, it’s usually easy to notice that an invisible unit is killing your troops, but it’s not as easy to know what to do to detect that unit.

The interesting aspect of these abilities is that their usefulness is based on the opponent’s access to a counter to the ability. Adding these kinds of abilities is more a question of technology tree balancing than unit balancing, and may require some player education due to the aforementioned problem.

3 Responses to “RTS Game-play Part 6: Visible Balancing”

  1. Spencer Hedeen :

    Hi, there. I am quite knowledgeable on game design and theory, and I wanted to express my idea for an interesting way to implement cloaking and detection in an RTS game.

    Stealth units, or units that could cloak, could have a radius of cloaking safety (i.e., a visual indicator of how bold said unit could be around opponents). If that unit’s cloaking safety radius overlaps another unit’s detection radius (which would work in the same way), the stealth units would be revealed.

    In this matter, both stealth and detection could be implemented in a more intriguing way, with degrees of intelligence/counter-intelligence rather that set ‘cloak’ and ‘detector’ special abilities. It might add an entire new level of strategy to a game. I hope you agree. Thanks!

  2. Marco Afonso :

    Deffenetly, units balacing are the active core of any RTS game.

    Every variable counts, as well all the possible combinations.

  3. X3M :

    Hey there. I’ve been reading your article. You are displaying a lot of good points. Perhaps you should combine it all in 1 document and upgrade this document from time to time.

    3 additions:

    1. I do want to give you another “visible balancing” point. Which has proven to be very important. It’s unit size. Try halving the size of a certain unit, and see what effects this has on the range. A unit with range 2 and size 1 will have the possibility of 2 units in a row that are attacking. With size 0,5, there will be 4 units in a row. This is only in 1 dimension (lenght) for clashing armies. For surrounding another unit, you get 2 dimensions, and size 0,5 will result in 4 times more units that can attack. An example with melee range is zerglings, vs other units. There aren’t much around 1 marine, but a lot more around a structure.

    Another example is passing through terrain. Small units can pass more easily through terrain then big ones. Try moving 3 ultralisks up a cliff or a swarm of zerglings. You will notice difference. Flying units are often singularities in games. Stacking infinite on one and another. This is why a lot of people find the starcraft air imba. This changed after the splash addition in brood war.

    2. Some games have the cooldown placed before the shot. For example, the NOD obelisk of light has to charge up. If this wasn’t the case, the structure would cost a lot of more. A smaller lesser noticable case is the grenadier which has to throw the grenade first. You can dodge both units by moving away.

    Slow projectiles which still hit are somewhere between the dodgeble projectiles like artillery and instant hit projectiles like bullets.

    3. Every factor that gets changed will influence other factors. For example, adding more speed will also result in surrounding another unit faster. This in combination with unit size would result in an exponential increase. Adding more health will increase damage effects as well.

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