Dota 2's Crown Fall Act 3: The Frosts of Icewrack arrived last night, and in addition to a new overworld map, "collector's cache" items, and a new comic that advances the story, there was a very surprising surprise: a full-fledged fighting game.

Called Sleet Fighter, the mini-game follows the expansion's snow theme (and, of course, popular fighting games you may have heard of) and can be played from within the Dota 2 client.

As VG247 points out, players choose one of five Dota 2 heroes-Marci, Bristleback, Tusk, Vengeful Spirit, or Dawnbreaker-and face off against other characters in classic 2D fighting action.

It's not a full-blown fighting game that would make someone at Capcom break out in a cold sweat, but it looks pretty good for a surprise addition to the battle path. Each character has a unique move list and alternate skins, and both single-player and PvP matches are supported online and locally.

Courtesy of YouTube's Elkun Coding channel, here's the action:

Some Dota 2 fans on Reddit think that Sleet Fighter's surprise was inspired by Riot's fighting game 2XKO, or a Some believe it may be a reaction. Others speculate that it is a test to see what kind of reaction it will get: if players really like the game and there is enough demand, Valve might put serious resources into this mode and make it stand on its own as an independent game. That seems more likely and more in line with Valve's approach: do something, see what happens, and respond accordingly.

If you are not currently a Dota 2 player, but are interested in the new fighting game, you can find the full Crownfall event at dota2.com. And it looks like you'll have a little more time to enjoy it than previously expected: Valve also announced today that it has decided to extend the event through October, given that "the event has grown (and continues to grow) bigger than we originally imagined."