For the moment, only a small number of players in Europe will be able to participate, and this will be a totally blind trial. In other words, players will have no idea that they have been associated with AlphaStar. This will help to ensure that all games played against the superpowerful AI are under the same conditions. Winning or losing against AlphaStar will affect the MMR of a player, as usual.
In order to play against AlphaStar, you can click the "accept" button in the game pop-up window. If you change your mind, you can select the "DeepMind Opt-in" button in the 1v1 menu. AlphaStar will play in the latest version of StarCraft IIand will play as or against Terran, Zerg or Protoss. Players will be matched according to normal match rules.
The experiment is part of DeepMind's "ongoing scientific research on artificial intelligence," and the results will eventually be published in a peer-reviewed scientific article. Repeats of the matches will also be published. For a demonstration of how AlphaStar works, watch the video below from DeepMind.