If you hear people talk about a real-time strategy game with "massive numbers of units fighting" you can be sure they are talking about Supreme Commander. The unofficial successor to the Total Annihilation Series completely redefined some aspects of the RTS genre. In Supreme Commander you can zoom out so far that you can see the whole map on your screen and units are just little blips. This is much needed in fights when several hundred units go at each other. Supreme Commander is also one of the most demanding RTS games with support for up to four CPU cores - a dual-core system with high-end graphics is recommended for optimum game play.