No revenue estimate for GOG — its rating/review counts don't calibrate to sales the way Steam's do. The Steam version is estimated at $31.5K — a different platform, not this one.

X-Com: Interceptor

They're back... only this time, the heinous aliens are out to destroy Earth and rule the new frontier. As X-COM commander, it's your sole duty to protect humanity and the prized mining operations in outer space. You must strategically equip your X-COM fighters, amass a formidable arsenal and then fulfill your mandate by going head-to-head with the devious element. The action is fast. And the opposing forces are wicked. But if you are smart, diligent and quick, you will prevail in a masterfully fought campaign to save our planet from perilous collapse. Wreak complete destruction in an addictive and seamless combination of combat action and strategy. Mastermind your plan by purchasing equipment, hiring pilots and researching new technologies. Pilot your own X-COM attack ship in a face-to-face 3D real-time first person environment.