Though war2 mpq i found sc stuff in War2 mpqs.
That tells me either sc started to get built off of war2. Or Sc stuff was removed and not all though then added war2.
Also sc is iso graphics not like war2. All mostly the same with different pictures. And sc had triggers and shit that was added onto the engine.
And I also could have swore the developer said most programmers move on to starcraft to rush it's development. That's why it crashed alot....
Source
http://starcraft.wikia.com/wiki/WarcraftWarcraft: Orcs & Humans and Warcraft II: Tides of Darkness were Blizzard's first RTS games in the series. In these games the two sides had units and buildings with identical statistics, save for the spells for casters. Thus, both sides played more or less the same way.
StarCraft represented a departure from the first Warcraft games. While there were now three sides, the major difference was each had units and buildings with unique statistics. This meant each played differently. In addition, one has to play all of the races to get the whole story. This concept was adopted for Warcraft III: Reign of Chaos although now with four sides.
During early development, StarCraft used the Warcraft II engine. The initial cold reception, demonstrated by the phrase "Orcs in Space", led to shifts in design and gameplay.
Both StarCraft and Warcraft games make use of Blizzard's Battle.net online gaming service, with the exceptions of Warcraft I and the DOS version of Warcraft II. Warcraft II: Battle.net Edition was released to support Battle.net, run under Windows, and include many features introduced in StarCraft.
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So it's possible your clan did exist with starcraft the year of release because it came with battle.net on release. Then they patched war2 to bnet and other games.
But you are wrong sc was made from war2, you can tell by the screen shots of sc alpha and stated above.. they didn't say they ditch it but kinda hinted it. I think they just made updates to the war2 engine and built it into starcraft.
When I reverse sc and war2 they are similar.....
Left is when they used the war2 engine with sc graphics
Right is after they tweaked the engine and made changes.