Pokemon Go, the augmented reality game that has become an overnight sensation, experienced sluggish performance over the weekend, possibly from a hacker attack on its login servers. Shortly after Pokemon Go devs tweeted that the game was rolling out to 26 additional countries, this tweet appeared: "Trainers! We have been working to fix the server issues. ... We'll post an update soon." The next day the Pokemon Go team announced that the issues causing the server problem had been fixed.