When it comes to measuring a person's performance on a keyboard, "words per minute" is the standard by which many a typist has been judged. But for pro gamers who also live and die by the keyboard, there's another brutal metric that determines who can make it to the top of the competitive ladder for a game like "StarCraft II": actions per minute, or APM.
"Most professional players can get up to five or six hundred actions per minute," Philip Hübner, a product manager for the e-sports league Intel Extreme Masters, told NBC News. "That's 10 actions per second."
For the uninitiated, watching a professional league video game tournament can be a dizzying affair. At a recent tournament in New York, early attendees looked on with outright confusion as two players squared off against one another from opposite ends of the stage. Each player was housed in a tiny windowed booth where they sat, their faces blocked from the audience by large computer monitors. All you could see of the player during the actual games were their two hands — one on the mouse and the other on the left side of the keyboard, both moving at a blinding speed.
Matt Weber, director of operations for the online e-sports community Team Liquid, told NBC News that he thinks about it like a baseball player's pitching speed — for pro gamers, there are certainly factors other than sheer velocity, but it's an important first standard to determine who can make it to the top in the first place. And while APMs might be measured for curiosity's sake in other games, they're more important in "StarCraft II" than any other e-sport simply because the game itself is so complicated.
In a fast-paced multiplayer online battle arena game like "League of Legends" — the other major title on the professional gaming circuit — the player only controls a single hero, who runs around the map casting spells and killing bad guys.
But in the real-time strategy game "StarCraft II," a player must control hundreds of units: building defenses and gathering resources to produce soldiers, then mustering troops for battle, attacking and defending across multiple fronts. Each unit costs money, and a rock-paper-scissors-style logic makes every lightning-fast decision high risk. Games are often determined by which player is nimble enough to adapt to his opponent's forces.
"The way you talk about a player physically is similar to how you talk about a baseball player," Weber said. "It's always their mechanics. Mechanics in 'StarCraft' refers to a player's speed, accuracy, ability to multitask, and efficiency."
Comparing himself to the pros, however, Weber said the speed isn't as important as what the player can do with it.
"A guy like me can hit 300 APM easily," Weber continued, "but it's mostly wasted because the way I get there is just to click a lot, most of which are redundant actions — for example when I click for a unit to move I'll spam it 10 times to keep my speed up."
In "StarCraft II," the player keeps one hand on the mouse while the other remains firmly planted on the left side of the keyboard to be able to reach any number of hotkeys that are tied to particular actions instantaneously. Who has the upper hand in a "StarCraft II" match can change in a matter of seconds, so a misplaced keystroke can be the difference between victory and defeat at critical moments.
"A good player will click once for everything and jump back and forth on the map a lot to control units at his opponents' bases as well as direct around units at home," said Weber.
He sends me a famous video of Korean player KangHo (see above) to illustrate how nimble and dexterous a pro has to be at this point in the game's history. Just watching the video and trying to imagine moving across the keyboard that quickly practically makes my wrists ache. Which raises an interesting problem for the "StarCraft II" community: how do players manage to stay at the top of their game and remain healthy at the same time?
For many, it's a tricky balancing act. Weber said that top players have had to step away from the game because of wrist injuries or adjust their play style to support slower strategies. Benjamin Baker, 23, who plays under the handle "deMuslim" for the team Evil Geniuses, told NBC News that he has to maintain himself physically like any professional athlete by taking vitamins, making sure his hours "aren't insane," and stretching regularly — things that might surprise those unfamiliar with the skill required to compete professionally.
"The stereotype of gamers is that you're fat and have long hair and you sit in your basement all day playing games," Baker said during the IEM competition. "Have you seen anyone (at the tournament) that fits that stereotype?" (Answer: No, we did not.)
Still, Baker identified another concern that's common among e-sports athlete: the fear of burnout. Playing at such a high level requires practicing (i.e. playing the game) for 8 to 12 hours a day. And after doing that for almost a decade (he started playing "Warcraft III" competitively when he was 15), Baker admitted that he's feeling more than a little tired.
"I need to recuperate, find new styles, get better again," Baker said.
As with any sport, however, the intense physical demands are part of what the fans admire in their favorite players. Weber of Team Liquid said the speed of "StarCraft II's" gameplay means that there's also a quick turnaround in who's considered the top players — strategies are constantly tested and reinvented at a rapid clip, with older or slower players falling behind as younger ranks rise above them.
"It's one of the cooler aspects of the 'StarCraft II' world and one of the parts of it that I really love," Weber said. "It's always awesome to see new guys rise up through the ranks and become strong tournament players."
Yannick LeJacq is a contributing writer for NBC News who has also covered technology and games for Kill Screen, The Wall Street Journal and The Atlantic. You can follow him on Twitter at @YannickLeJacq and reach him by email at: Yannick.LeJacq@nbcuni.com.