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.