These cheats work on Mechwarrior 2, Ghost Bear's Legacy
and Mercenaries, all three games in the Titanium Trilogy
 

Hold CTRL+SHIFT+ALT and type:

su        Invulnerability toggle
is        Unlimited ammo toggle
oo        heat tracking toggle
it        Nuke current target
re        Destroy current target
in        Jump jets
cr        Unlimited jump jet juice
li        Ends mission succefully
be        Free-Eye mode