No revenue estimate for GOG — its rating/review counts don't calibrate to sales the way Steam's do. Reviews and prices only.

Prophecy I - The Viking Child

Cartoony side-scroller where you take the role of, as the title states, a viking child, in his quest to free his friends and family, held by the evil god Loki inside the Great Halls of Valhalla. Fight your way through 16 levels with diverse scenarios, including medieval castles and mountains. Spread throughout the levels are shops in which you can buy potions and other magical items to help you along the way. Before you finally face the Dark Lord Loki, you must also defeat the 8 Apprentices of Darkness. The game features colorful graphics and 22 different tunes to make the whole trip a bit more pleasant.