En:
Hi GOG.com. Do you plan to sell the game "Re-Volt", which would be fully compatible with Windows 7? I think not only I would like it to play on a modern operating system. (Google Translate)

Ru:
Привет GOG.com. Планируете ли вы продажи игры "Re-Volt", которая была бы полностью совместима с Windows 7? Думаю, не я один хотел бы в нее поиграть на современной операционной системе. (Original)

It seems to be currently controlled by throwback entertainment, so it's entirely up to them if it will be released here. Seems to have quite a dedicated following though.

Isn't the game freeware?

Even if it is freeware, gog would still need to get permission to release it.