The old versions of DogFight are now included in the game.
You can start them through the game or find them in the game folder /olddogfight.

The two most popular versions of DogFight are now Open Source.
You can find the sourcecode on GitHub:

• https://github.com/Nosceteipsum/DogFight3
  
• https://github.com/Nosceteipsum/DogFightUltraDeluxe

if you have any questions feel free to contact me and I will do my best to help.

The game is live, enjoy destroying UFOs and go compete with your friends.