Heroes of Might and Magic III on iOS and Android.

Lider1, to put it briefly: as far as I know, VCMI is based on the WoG engine. It already works on tablets (there are videos on YouTube demonstrating this: 1 2 3). But the creators of VCMI also don't have the original "Heroes" source code: they use reverse engineering.

The fact that some people offered to buy the "source code" from the rights holders, but received the answer: "there isn't any!", supports the idea that the "source code" for "Heroes" is hopelessly lost. And if they did exist, it's unlikely that anyone would miss the opportunity to make some money by selling something that's just lying around unused.