Here is the list of unreleased games that have been leaked on the internet:
● Half Life [100% Complete]
● Propeller Arena [100% Complete]
● HellGate
● System Shock 2 (Small demo)
● Flintstones Viva Rock Vegas [100% complete but with bugs]
● PBA Bowling, Geist Force [100% complete with online mode]
● Geist Force
● Toejam and Earl 3
● ECCO 2
● Millenium Racers Y2K fighters [100% Complete]
● Agartha
● Ball Breakers [100% Complete]
● European Genesis Emulator [100% Complete]
● BleemCast Beta
● Internet Game Pack [100% complete with online mode]
● Test Drive Cycles
● Flight Simulator
● Heroes of Might and Magic III
● Ring: The Legends of Nibulgen [only the GD 2 of 3 has been found
● The Simpsons: Bug Squad
● Take the bullet
Out there somewhere, I know there is Deer Avenger.