Briefly: The most imbalanced StarCraft unit isn't in StarCraft. It's this Colossus, recreated in Besiege, by TheAmazingTwist. It's imbalanced... in a different way:
Pumped up the power of the balloon in the middle to about 60, otherwise it would crumble under its own weight. The downside is that it makes everything bouncy.
I started off wanting to just make the model, then after some tinkering managed to kind of make it walk. It's very tricky and most of the times fails, but it's an extra feature.