Everything you need to know about the world of professional gaming, which is on track to be bigger than football one day

Whether or not you see the appeal in watching strangers play video games, there's no denying that eSports are a phenomenon.

With about as many global fans as ice hockey - a base expected to swell to American football's bloated proportions by 2017, according to a report from the gaming market research firm Newzoo - eSports are definitely the big leagues. 89 million people watched eSports tournaments in 2014. That status comes with crowds, drama, glitzy stadiums, and even doping scandals. 

Twitch.tv is by far the most popular streaming service for spectator gaming, and last year it sold to Amazon for $970 million. eSports are big business.

The word "eSports" doesn't actually refer to a single kind of event: It's a catch-all term for professional video game competitions, ranging from first-person shooters to high-level team strategy games. For the purposes of this article, we're going to group together the disparate parts of the world of eSports.

The eSports' super-genre

The biggest tournament in eSports is happening right now in Seattle. That's The International 5, the official annual tournament of beloved game "DOTA 2" ("DOTA" stands for "Defense of the Ancients" - a modification to Blizzard Entertainment's "Warcraft" franchise that became its own game).

This is what "DOTA 2" looks like:

There's more than $18 million on the line in this tournament, built around a game that was never meant for casual players. Like many real sports, a big chunk of "DOTA 2" fans don't actually play the game. But they love to root for their favorite teams and watch elite players compete.

"DOTA 2" is what's called a Multiplayer Online Battle Arena game (MOBA). This genre is especially well-built for eSports because, like tennis or basketball, it comes with standardized playing fields and leaves little to dumb luck.

Wikimedia CommonsA map of a typical MOBA map.

MOBAs, in general, work like this:

• Two teams of players choose characters with specific roles.
• Each team has a base to defend, and attempts to destroy the enemy base.
• Most of the action occurs along "lanes" linking the two bases.
• Computer-generated players spawn and fight alongside player characters.
• Players view the game from a top-down perspective (seen above).
• Often, defensive towers along the lanes form additional obstacles to assaults.

This standardization produces the same kind of coordinated team strategy and drama that makes major team sports so compelling for fans. Just like soccer, football, basketball, and hockey have the same fundamental rules (put ball/puck in opponent goal area) but wildly different gameplay, so too do MOBAs function according to like principles but play very differently from one another.

If "DOTA 2" isn't your jam, you might enjoy "League of Legends," the subject of ongoing Tech Insider documentary series "League of Millions":

The fastest players in gaming

BlizzardThis still is from "StarCraft."

The hottest game outside "DOTA 2" and "League of Legends" is "StarCraft." At a quick glance it might look like just another MOBA, albeit with much older graphics.

But "StarCraft" is another thing entirely: a real-time-strategy (RTS) game. That means players control many more units than the single characters ("heroes") of MOBAs. Often, you control whole armies.

All of the units on both teams can move and battle at the same times. This means a great "StarCraft" player is more Bill Belichick than Tom Brady, keeping track of broad goals many moves ahead even as they micromanage every detail of the game.

Pro-level "StarCraft" players manage a couple hundred distinct actions in a minute - or several per second. Here's one in action:

"StarCraft" is mostly a big deal in South Korea, where thousands of players line up to watch major tournaments. This isn't altogether different from "DOTA 2" tournaments in the US, though eSports are very much a part of the popular culture in South Korea. (That unfortunately doesn't stop Americans from writing about it like some strange, particularly Korean national insanity.)

When you just want action

First-person shooters, despite being among the most popular games on consoles, and despite being full of standardized maps and objectives, have struggled to grow audiences for professional play. But first-person shooters are difficult to watch for precisely the reason they are so fun to play: their engines put you in the middle of the action.

MOBA and RTS are played from a top-down view that closely resembles the perspective you might have on a professional sport. A first-person shooter, though, has a far more limited perspective - the rapidly shifting point of view of a single player swinging her weapon around.

Sure, it can be cool to watch sports that way:

But imagine keeping that look for a whole broadcast. It'd make you dizzy.First-person shooters may be on the verge of a huge breakthrough though. Microsoft announced plans on Tuesday for a "Halo World Championship" with a million dollar prize. "Halo" is a massively popular franchise with an ocean of ridiculously talented players ready to compete - so it's already ripe for professional competition. The most salient part of their pitch though? The new "Spectator Mode" intended to improve viewers' experiences.Still, the footage is pretty dizzying:It's hard to get a sense of the overall game from that perspective (or hold on to your lunch).

Fighting games

The last major eSports genre: the good old fighting game. Like real-world mixed martial arts, fighting eSports aren't about grand long-term strategies or teamwork. They're about two people, in a room together, beating each other up until a clear winner emerges.Fighting eSports are also unique because their top titles tend to be pretty popular with casual players, who can follow the action without much jargon or effort. "Super Smash Bros," though is the genre's most approachable title, and has the widest demographic appeal. The comparably brutal "Street Fighter" is the most popular competitive fighting game, and has a new release coming in 2016.But just about anyone will recognize at least some of these characters from "Super Smash Bros. for Wii U" - including one pugilist from the "Street Fighter" series making a cameo:

That accessibility, plus its wild gameplay, make it a great introductory eSports game.Of course, like any fighting game, "Smash Bros." has its deep controversies. But rather than debate if Ronda Rousey helps or harms the sport, or argue over Pacquiao and Mayweather's checkered pasts, fans get bound up in the relative advantages of different characters.In the ever-expanding "Smash Bros." world, each character has special abilities and weaknesses. The games' creators work hard to balance them against one another, and at the level of typical players' button-smashing their efforts are usually successful.

But elite players skill can reveal differences at the margins. Players freaked out when the character Diddy Kong turned out to be a bit overpowered in 2014 - until Nintendo rolled back his strength. Now the decision to include custom moves in the game may have produced an overpowered Pikachu:

Players are calling the fallout the "customs civil war."

So, are you pumped to go out and watch eSports?

If you find yourself eager to watch champions of your favorite game battle it out, look up major tournaments and exhibitions. Pro gaming goes beyond the genres we've listed here - every title from "DayZ" to "Madden" has its professional players. (And we haven't even touched the legion of players who earn money livestreaming outside official competition.) And almost every eSport streams on Twitch.tv, along with commentary and analysis.

Whether or not you find yourself drawn to watch elite gamers compete for cash, eSports are a cultural force and they're only growing. With blockbuster titles like "Halo" now bent in the service of professional gaming, there isn't much room left to pretend its just a niche hobby.

And with the violence, life-altering injuries, scandals, and declining viewership that define professional sports these days, maybe that's not such a bad thing.

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