halo 3 question?

[Frankie]

okay so i beat the game on normal
now i want to beat it on heroic but do i have to beat the whole missions on herioc or legendary or just the last mission

 

[dukenumberonefan]

to beat it on heroic or legendary you will have to play the whole game over on that mode either heroic or legendary and after completion you might want to try at online gameplay b/c it is friggin awesome