The final mission of chapter 3 is “Internal Purge.” It is the 18th mission of the game.
Aerial Interdiction: Use the BurnOgoto mech.
When the mission starts, Use the ER-0200's to shoot down the 8 transport helicopters(they are the bigger helicopters). There will also be 4 or 5 fling normals shhoting at you, which you can either destroy or ignore, you're choice. Keep shooting the helicopter until the mission says "enemy transport is on the ground and moving quick", look for the train transport on the tracks on the ground to the left from where started on the bridge. Once you see the train, shoot it a few times with the OGOTO's on your back to destroy it. Also, be sure that no transport helicopter get by because you'll fail mission if that happens. On Hard, there will also be an enemy air fortress to destroy also. Just shoot it with the OGOTO's while doding to destroy. Do it quick because the train transport is still on it's way.
Icebreaker Defense: Use the BurnOgoto mech.
When the mission starts, switch to the OGOTO's and wait till you see a red dot appear on the radar. Once the red dot appears, boost over to it and destroy with once shot from the OGOTO's. Repeat this pattern until all submarines are gone.They appear in the same order and place everytime, so play it a couple of times to get used to where exactly they pop up at. There are only 8 submarines to destroy, so it should be easy to do. On Hard, there will be about 5 flying drones shooting at you, just ignore or destroy,your choice.
Water Gliding: Use the BurnOgoto mech.
When the mission starts, switch to the OGOTO's and boost to the first ship just beyond the buildings. Than proceed to destroy all the other 3 ships. Just ignore the enemies around you and concentrate on the ships. On Hard, Just do the same as on Normal difficulty, but this time there will be 7 ships to destroy with the OGOTO's.
Might Makes Right: Use the BurnOgoto mech.
When the mission starts, destroy the enemy in front of you, than proceed into the first tube. Boost straight up, than half way turn around and go into tunnel. Once you come out of the tunnel, drop straight down and proceed through the tunnel in front of you, but watch out for the enemy with the BIGSOUX equipped. Once get to the end of that tunnel, drop down again and go forward. The last 5 enemy Normals are scatter throughout the tubes and tunnels. On Hard, do the same as on Normal difficulty, but this time there is 9 Normals you have to destroy.
Barbe-Bleue: Use the BurnOgoto mech.
When the mission starts, switch to the OGOTO's and watch the radar. Whenever you see red dots appear on the map, boost as quick as possible over to the red dot and destroy with the OGOTO's. Just keep doing this pattern until all enemies are gone. On Hard, It's the same as on Normal difficulty. Just remember to be real quick and efficient.
Retaliation: Use the BurnOgoto mech.
When the mission starts, switch to the OGOTO's and boost over to each enemy group and destroy them with the OGOTO grenades. There will also be a few Normals that fly and boost, plus a couple Normals on a hill shooting missiles. On Hard, There will also be an enemy walking fortress. Just destroy the walking fortress with the OGOTO's and that about it.
A Dark Night's March: Use the BurnOgoto mech.
When the mission starts, switch to the OGOTO's and boost forward a bit until you find enemies on your radar. There will also be flair's being shot up into the air to help with visibility. Just keep killing enemies until you find an enemy walking fortress, destroy it quickly to end the mission. On Hard, there will be a few more enemies and there are also 2 walking fortress's to destroy.
Up In Flames: Use the BurnSirius mech.
When the mission starts, switch to the Sirius cannons and than just locate the enemy NEXT(he'll be the one boosting and shooting missiles) and melt him with the Sirius cannons. On Hard, it's the same as on Normal difficulty. Just be quick and efficient.
Internal Purge: Use the BurnOgoto mech.
When the mission starts, switch to the OGOTO's and proceed throught the tunnels to each of the 3 objectives, destroying the enemies along the way. Once you reach one of the objectives, destroy it with the OGOTO's from a distance. Do this for all 3 and that's it. On Hard, It's the same as on normal, but after you destroy the 3rd objective, there will be an enemy NEXT coming from the tunnel that you came from. Just destroy the NEXT with the OGOTO's and that's it.