BI-MU ka-blam!-aku
FURASSHUBAKKU ni yatsu no kage
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Though the idea is good, it has been used before, as mentioned by other posters. Take Battlefield 2, for example. The commander may plot commands then jump into the action to lead as a CO.
The rendering power required isn't hard to gather. My busted laptop can run Battlefield: Bad Company 2 on a 32 player giant map (ie. Heavy Metal) with no problem. The Xbox, or it's incarnations? Piece of cake. It can be done!