Links for manual installation:
Horizon for PC (Linux, x64, .tar.gz)
Protocol definition for connecting to the FlightGear flight simulator
Readme: How to set up the FlightGear Flight Simulator with Horizon
*Note: It is recommended to download Horizon for Android via the Google PlayStore and for iOS via the AppStore. After installing “Horizon – Your Portable Glass Cockpit”, you can create and use your account with all functionalities for two months free of charge. After the first two months a payment is required to continue using your Horizon Account for 149 Euros/year (approximately 169 $/year, depending on the current exchange rate). An account is required to get support such as help, regular chart/terrain updates, etc.