In a report from ArsTechnica, Blizzard revealed that they were pretty much forced to develop the entire game from scratch, thanks to the fact that a lot of the original code and assets for the original Starcraft had been lost. This meant that they had to pay attention to a lot of the details from the original, including weird lighting effects.
According to Blizzard 3D Art Director Brian Sousa, the entire project was “eyeballed” as “We had no code and no art assets.” The team was forced to rebuild the game based on concept artwork, sketches, original boxes, manuals, and so on, although thankfully they did have access to backups of the original audio files.
Regarding the details such as replicating the weird lighting effects, Sousa adds, “Shadows are in the wrong places, and lighting is different across the board. But we wanted to make sure that going into StarCraft Remastered, that [players] recognize everything instantly.” StarCraft Remastered is currently set for a release on the 14th of August where it is priced at $15.