After beating all the field training missions, you unlock the War Room, Campaign, Design Maps, and Stats options.
Hold select when choosing Campaign mode to play advanced mode.
After beating the Campaign mode, you can purchase additional CO's.
Beat the campaign with these requirements to unlock the following:
Select Max for mission 4
Beat campaign mode
Beat sonja missions 12,13, and 14 by beating mission 9 in 8 daysor less, 10 in 10 days or less, and 11 in 12 days or less NOTE: You can't unlock Drake and Eagle in the same campaign
Beat rivals mission by selecting Sami for Captain Drake, Naval clash, Wings of Victory, and Battle Mystery
Select Andy for Captain Drake, Naval Clash, Wings of Victory and Battle Mystery, then beat campaign
Purchase all above COs
Unlock and purchase all COs including Sturm. And finish the Advance Campaign mode. CO Nell should be available for 80 Coins
Kanbei Arrives! in 8 or less turns
Mighty Kanbei! in 10 or less turns
Kanbei's Error? in 12 or less turns
If you beat all of these missions within the time limit, you will continue into a hidden path in the story line