How to run the game on 16:9 monitor with correct aspect ratio?

Superfrog doesn't actually run in 16:9. The game was developed well before 16:9 monitors were common on the market.

You can, however, modify the game's DOSBox configuration so that it doesn't stretch it (assuming that you can't do this in your graphics card driver config or from your monitor):

1. Go into the Superfrog directory (something along the lines of C:\Program Files\GOG.com\Superfrog)
2. Open the file dosboxSF.conf in Notepad.
3. In the [sdl] section, change

fullresolution=Original

to

fullresolution=1280x768

4. You might need to change aspect=false to aspect=true

Thank you, it working perfect now.

In C:\Program Files (x86)\GOG.com\Superfrog theres an orange icon called "Graphic Mode Setup"