Here's a guide on how to get this working as I had issues.
1. Unzip to a folder in the root of your drive.
2 Rename the folder as the "E" in the word demo is a symbol and some AV products don't like it. So rename to "Dragoon-Demo-V2"
3. Run game.exe int he folder and boom, it works.
Don't forget, Alt+Enter = Full screen and the language is not English but it's worth playing.