Random message
Go to "Settings" at the main menu, then press
[Y] to create a new profile. Enter ".fortune" (note
the period character) as a name. As soon as you enter the last
letter of the name, a strange random message will appear. Every
time you enter this name, you will get a different message. ".fortune"
is a reference to a feature on the Linux/Unix operating system.
Alternate ending sequence
Successfully complete the last level of the game in
campaign mode under the legendary difficulty setting. The new
ending features a human and alien fighting hand to hand. The human
will say "Its over", and then they hug because they
know the explosion will kill them both. Also, the FMV sequence
of each battle scene will be slightly longer.
Alternate dialogue
Playing under the legendary difficulty setting introduces
new dialogue not heard in other modes. For example, after being
massacred by a force of Grunts, Jackals and Elites, one of the
grunts asks, "Can I have his helmet?". Also, your fellow
Marines seem to be a bit more chatty (as well as profane).
Under the legendary difficulty setting, view the entire first
FMV sequence. During the sequence, the General says things very
differently when compared to the sequence under the easy difficulty
setting.
Final ending scene
Successfully complete the game on any difficulty setting
and wait for the credits to end. The game will show the Monitor
fly across the screen and laugh.