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 $5.1K — a different platform, not this one.

Veil of Darkness

LIFT THE VEIL OF DARKNESS AND ENCOUNTER THE NEW FACE OF HORROR! Bloody from the flaming wreckage of your cargo plane, you stagger into a desolate village in a time-forgotten valley. With each step, you slide deeper into a horror beyond reason. A terrifying tale unfolds - of Kairn, a man compelled to murder his father and brothers. A man with an all-consuming lust for power. A man who feasts on human blood! You must destroy this blood-mad demon and his flesh-devouring ghouls and werewolves. Or you will die. Will you be the final victor? Or Kairn’s next victim? Unravel terrifying riddles. Fulfill bone-chilling quests. Clash in a deadly face-off with the vampire Kairn. Fight for your life in one of three combat levels. Use the right weapon to destroy each ghoul, werewolf and zombie. Or die. Meet a host of spectral characters whose dark secrets reveal more of the mystery. Sink deep into this gothic nightmare adventure with state-of-the-art gameplay. Record every step you take in dungeons with line-of-sight auto-mapping and print-out features.