IPod game steps towards entering the video game handheld console market. Even video game magazines like GamePro and EGM have reviewed and rated most of their games. The games are in the form of .ipg files (iPod game), which are actually .zip archives in disguise. When unzipped, they reveal executable files along with common audio and image files, leading to the possibility of third-party games. Currently, Apple has no publicly available software development kit (SDK) for iPod-specific development. The iOS SDK covers only iOS on the iPhone and iPod Touch, not traditional iPods. As of October 2011, Apple has removed all the
IPhone 3GS more favorable reviews mainly because it comes pre-installed with iOS 4. Jason Snell of Macworld praised the iPhone 3GS, saying that "the device's internal changes shines in the iOS 4 update, making the iPhone 3GS a worthwhile upgrade compared to its predecessor although a little too late compared to the iPhone 4." TIPB stated that "aside from hardware specific features like FaceTime, Retina Display, and gyroscope support, the bottom line is iPhone 3GS users are getting the same software that makes the iPhone 4 great." Shortly after the release of the iPhone 3GS, some users reported overheating of the device