The unit triangle that is mentioned in the title of the guide refers to the three tier one units from each race. Tier one refers to the elementary level of unit production, meaning the very first military structure that can be built. These buildings are the Barracks for the Terran, the Gateway for the Protoss, and the Spawning Pool for the Zerg. The units that are available from these buildings at tier one are the Terran Marine, Protoss Zealots, and Zerg Zergling.
The Marine is a ranged unit, costing 50 minerals and spawning with a squishy 45hp. It deals 6 damage rather quickly at a modest range. The Zealots costs a whopping 100 minerals and is well built with 100hp and 50 shields. The Zealots attacks with psi blades, dealing eight damage twice at a moderate speed. The Zergling spawns as a pair for 50 minerals, each having 35hp and dealing 5 damage very quickly at a melee distance.
It is easy to see how different each race is just by looking at their first units. It is easiest to compare similar units so we will start with the Zergling and Zealots. Both are melee ranged units but that is probably about it when it comes to similarities, sadly. A Zealots is obviously stronger than a Zergling but what about cost for cost? It takes four Zerglings to kill a Zealots in an open area, 100 minerals vs 100 minerals. This is when Zerglings are allowed to surround a Zealots, allowing all four to be attacking the Zealots while the Zealots can only hit one at a time. In a choke, or any scenario where a Zealots can’t be surrounded, it takes an extremely large amount of Zerglings to kill a Zealots because they will be engaging in a fight where the individual stats of the units are being compared. A Zealots will kill a Zergling in three hits, while it will take 35 hits from a Zergling to kill a Zealots.
When we look at a Marine, his stats are very modest when compared to a Zealots or a Zergling. A Zealots carries much more meat and his harder to kill than the squishy Marine, while the Zerglings, although squishier, put out enormous damage per second. This is simply because the Marine is a ranged unit, meaning he can hit melee units from even before they can have the chance to attack back. The special thing about ranged units is that they are always contributing in damage output in a fight. When we look at the previous example about a Zealots in a choke against many Zerglings, because Zerglings are melee ranged they can only attack one at a time, because only one Zergling at a time can reach the Zealots. If a mass of Marines were to engage the Zealots, the Marines would not have to fight like the Zerglings and they will each shoot the Zealots. Because of this, there will be a point in time where Marines will be able to beat Zerglings and Zealotss cost effectively, even without micro, simply because they are all attacking at once instead of hitting only the closest units like Zealotss or Zerglings have to.
So the tier one triangle is balanced well, where each tier one unit can beat another tier one unit cost effectively in different scenarios. Although upgrades become available later for these units, the balance remains relatively the same.
In the next guide, we will discuss the tier 1.5 triangle.
