Originally Posted by
ssfsx17
Conterintuitively enough, you do the Single-Player Grand Campaign. However, you may notice that when you click on a faction's coat of arms, you "turn on" that faction to be playable by human. You click on the coat of arms again to turn off human control for that faction. You'll see what I mean.
Hotseat mode means multiplayer Grand Campaign using one computer. Each player gets one faction. At the beginning, you set a password for your faction so that (hopefully) nobody else can make your decisions for you. I used to play hotseat mode with my friends all the time until we realized that the shield bug made it very hard to have any interesting battles.