You are downloading the Slingy AppX file v220.127.116.11 for Windows Phone. Slingy is a free and fun Action & Adventure game: Welcome to the Slingy, the game where the build-in physics engine will provide hours of entertainment. Drag and release the ball to launch it. ... You can now download the offline AppX file to install & try it.
Download Locations for Slingy 18.104.22.168 AppX file
Note: To install it manually from an SD card, you should choose one of the server location above to get the offline Slingy AppX file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.