Tencent’s AI is now beating the most difficult bots in StarCraft II.

OK, so a computer beat a computer at a game. Why does that matter?

It matters because StarCraft II is an incredibly complicated game, and creating an AI that can play the game to a decent level is a tough challenge.

Players have to manage up to hundreds of units in real time, each with specific roles, in a game that typically lasts around 15 to 20 minutes. The key is to compose a versatile army that can expand, scout enemy territories, and attack opponents.

To play StarCraft II is to master resource management and quick strategic thinking. (Picture: Blizzard)

It’s tough enough for humans to play. Teaching a machine to play it is hard enough… and that’s before you consider their opponents.

Like many other games, StarCraft II includes bots that are designed to challenge human gamers. Some of them are even given special powers that regular players (and Tencent’s AI) don’t have.

For instance, while normal players can only see the immediate area around their units, bots in advanced levels have full vision of the entire battlefield. They also harvest resources more efficiently, so they can expand their base and grow their troops faster.

But powerful as they are, these bots are no match for Tencent’s AI. In a recently published paper, Tencent researchers revealed details of their two winning AI programs -- TStarBot1 and TStarBot2. According to the researchers, the stronger of the two AI programs won more than 90% of the top level games. Even the weaker program defeated the bots over 70% of the time.

The ultimate goal is to build an AI that can play StarCraft II better than humans. And Tencent isn’t the only one in that race. Another is DeepMind, the Google subsidiary that created AlphaGo -- the algorithm that bested a human world champion at the ancient Chinese board game of Go.   

But one thing that sets Tencent apart is that its AI was tested in full games (Zerg vs. Zerg in the Abyssal Reef map, if you want to know). DeepMind, on the other hand, has been working with mini games. These are easier versions of StarCraft II where players aim towards just one basic goal at a time, such as spreading units around a map.

Tencent’s AI might be faring better than other AI, but how does it match up against humans?

Not too well, it turns out.

In an informal showdown with four human players in the Diamond and Platinum leagues (i.e. the highest levels below Master and Grandmaster), the AI programs won only 4 out of 20 games -- so they’re not quite ready to face off with a pro.