Robotech: Invasion Cheats

After you beat the game, start a new game and select the Bygone Marshes level.

Turn around at the very start and there is a long area that you can drive through. So, drive through the pillars until you get to the last two sets of pillars. On one of them (facing north-east (use your compass) there is vandalism that says, "Jack Archer Lives!!"

If you shoot that particular sign, a health pack will drop, followed by protoculture, then a Holden Mark-2 Shotgun. There's one more item that comes out, but you have to keep shooting the sign until it does. If you do, you'll get a soccer ball. You can shoot it with the shotgun to make it bounce all over and test out the Havok physics engine.

During the fight with the Invid princess (Reflex Point), turn on the THERMO scanner. There is bright yellow spot on her right shoulder (everywhere else is blue). It's hard to hit, but it's the only spot that's not covered by her overshield. By killing the boss through this way, you unlock the third ending.