//Get JSON text file (Steam API)
$json = file_get_contents('http://store.steampowered.com/api/appdetails?appids=57690');

//Decode JSON
$game_json = json_decode($json, true);

//Target game name and echo it
echo $game_json['name'];

{"57690":{"success":true,"data":{"type":"game","name":"Tropico 4: Steam Special Edition"