Early versions revealed at E3 1996 shows that StarCraft was originally based off the WarCraft engine. The game shows graphics similar to Warcraft II: Tides of Darkness, such as the dashboard on the side, rather than on the bottom like in the final version. According to media, it felt too much like WarCraft II, with fans often calling the game "Orcs in Space" or "Purple WarCraft", among other variations. Due to criticism, Blizzard started reworking on the game, with a new engine.
The game lacked vespene gas at this point, and only minerals were available. The Zerg race was originally known as the "Nightmarish Invaders". The name was changed to "Zurg" shortly. However, a Disney Copyright claim made it finally change to "Zerg".
This screenshot closely resembles WarCraft II. Notice how the UI and art style are much different from the final game or even WarCraft II.