Awesome Game. So many innovations that haven't been repeated. Instead we've regressed back to 1998 gameplay with Starcraft 2 and Warhammer and all that garbage. Shameful how the simpler, dumber clickfest strategy games have triumphed over those which actually required thinking.
The underground tunnel system is still unrivaled today. You could literally have an army sitting beneath your enemies base waiting for the time to strike. You could control the weather and create a storm above your enemies base to screw up their radar. A full research and tech tree to actually create your own units that are tailored to the strategy you want to implement.