This time I will discuss a topic which is very game-specific, the topic of “macromanagement limits.” These are limits such as how much resources or how many units you may have. It strongly depends on what kind of game you are trying to make, and the technology you have available. If your game can’t handle path-finding for 1000 units at the same time, then maybe this limit should be included in your game design…

Macromanagement Limits

Macromanagement limit types, or macro limits, are obstacles that will prevent the player from getting too many units or too much resources. Examples of macro limits are unit supply used in Blizzard’s games and resource storage used in Command & Conquer and Supreme Commander (etc). Both these limits are upgradeable, and hence becomes a part of the macro itself.

Generally speaking, macro limits are not that good to gameplay. It adds things that the player must do that are not necessarily interesting or fun. For that reason, it’s important to make it interesting by letting it impact the player’s decision making, and offer a target for the opponent to destroy.

Unit Supply Limits

In games that use active resource gathering and multiple sources that can construct units, it can be a good idea to have unit supply limits. Supply limits will prevent the army from growing exponentially, and help balancing the cost of time (see previous post). During early-game the player will be forced to fill the supply with either military or economic units, and may choose to specialize on either. Unit supply limits may also improve your game’s performance, or at least prevent it from becoming too sluggish.

Starcraft also makes unit supply more interesting by adding additional functionality to the sources that increase the limit. The Protoss Pylon is used to enable other buildings, and the Zerg Overlord is a flying unit that can be used to detect cloaked enemies and transport units across the map. The supply limit is also used to give each faction a unique “feel”. On the contrary, they completely missed out on this in Warcraft 3, and made the unit supply limit very uninteresting and tedious.

In Dawn of War the unit supply limit is attached to the current technology level. That means that the army size grows as more advanced units are unlocked, and prevents the game from consisting of masses of level-one tier units. Though this kind of unit limit isn’t very interesting, it’s not tedious to player either. Some of the races have special kinds of supply limits, but in these cases they have multiple uses, such as acting as defenses or healing nearby friendly units.

Resource Limits

The other kind of macro limit is limiting resources that the player may have in stash. For example, the amount of money you are allowed to have in the bank is limited by the size of the bank, so you may be forced to buy a bigger bank if you are hoarding money. This kind of limit is quite poor and only penalizes new players to the game because a good player will know how to keep producing units. Also, the game’s feedback is usually incorrect – it will tell you to increase your stash limit, not to produce more units (which is the correct solution).

Frankly, all resource limits used in games so far have been bad. Take Supreme Commander as an example. The game has a passive income system that never runs out of resources, so having a maximum stash capability sounds like a reasonable idea. However, these buildings (mass and power storage) are not very interesting to build, and they are neither an interesting target for your opponent, since destroying them will not limit your capability to produce new units (you will still be more limited by the income from the passive resource gatherers). And finally, the mere appearance of the buildings in the user interface makes it more difficult to find the more useful construction options.

Lets say the game is about keeping a village running. If the game featured seasons, it would be quite fitting to have resource limits, such as saving up food for a harsh winter. They key is to keep it interesting.

Artificial Limits

As already mentioned, most games also include artificial macromanagement limits due to the finite processing power of our computers. An artificial limit is something imposed by the game, and can’t be affected by the players. In Starcraft there is an 1600 unit limit for all players, neutral units and mineral patches combined. If the unit count reaches this limit, all players will be unable to produce more units or buildings. In Supreme Commander this limit may be changed by the host, from 250 to 1000 units (including buildings) per player. In any case, these artificial limits are not intended to take effect, but are required in order to keep the game running.

Specific Unit Limits

This topic is related to unit balancing, which I will cover soon, but several games have limits on specific units in addition to other macromanagement limits. Usually the limit is “no more than one”, creating so-called “hero” units. Generally speaking this really hurts gameplay, because 1) too much focus is placed on the unit and 2) the unit is usually over-powered. Over-powered doesn’t necessarily mean imbalanced, but it means that when your opponent spots your unique unit, he must immediately devote all attention on attacking it, or countering it with his own unique, over-powered unit.

With that being said, limiting a unit type does make it less powerful. For example, imagine that the Protoss Arbiter in Starcraft was limited to only one at a time. The Arbiter is an expensive flying vessel with some very powerful spells (Stasis Field and Recall), as well as an area of effect that makes nearby friendly units invisible. If a player was only allowed to have one at a time, he would have to choose whether he wanted to use Stasis Field or Recall, since he wouldn’t be able to use both. Also, since the Arbiter takes such a long time to build and is so helpful for his main force, much devotion would be spent protecting it. However, it’s very difficult to protect the Arbiter from the EMP spell of the Terran Science Vessel or Lockdown of the Terran Ghost, so these counter-units would also have to be re-balanced as well. Needless to say, Starcraft would play a lot differently.

One game that heavily utilizes unique units is Dawn of War. Each army has a commander and a “relic unit”. These units are very powerful and take a central role in the player’s army (with a few exceptions, such as the Eldar Avatar of Khaine, who lives his life happily in the back of the base due to his passive powers). For example, let’s take a look at the Eldar Farseer. The Farseer is the commander unit of the Eldar, and she is mainly a spell-caster. The Farseer can be built already in the early game, and the player will almost always do that to counter the opponent’s commander (who also will be ridiculously strong). If you don’t believe me, play a game of Dawn of War with the Eldar faction vs a Space Marine opponent – without building a Farseer (or without using the Mind War spell) – and tell me how much fun it is.

The silly thing is that while the Farseer isn’t imbalanced, it would be easy to re-balance it to allow multiple Farseers (I’m ignoring Warhammer 40,000 canon problems now). Simply reduce her health and remove the most devastating of her spells, the Eldritch Storm. Multiple Farseers casting Psychic Storm (a weaker kind of spell) would obviously be fearsome, but the high cost of the unit (280 requisition and 80 power) and vulnerability to enemy fire would keep it maintainable.

In the current alpha build [note: this paragraph was written in August 2008] of Starcraft 2 the only remaining hero unit is the Zerg Queen. This is good news, because it means that both the Terran Thor and the Protoss Mothership have been re-balanced to allow the player to build several. Play-testers have reported that the Queen is fairly weak and can be killed by a small group of Terran Marines, so Blizzard seems reluctant to over-powering it. This also implies that the remaining reason why it’s unique is simply because it’s logical that a “queen” is the sole matriarch. Hopefully they will rename her, and allow the player to use strategies that involve building several.