This mission is extremely challenging. The Gattling Cannons and Bunkers are not as efficient as EMP Patriots or Laser Turrets for defense and surviving the tank rush can be a touch-and-go situation.
It is necessary to quickly turn your upgraded Overlords into your core defensive units, backed up by Speaker Towers to quickly heal them while they get lambasted by everything the Tank General can throw at them.
Just when you feel things are getting under control, enemy jets will attack your base. It is necessary to quickly add Gattling Cannons to beef up your defenses.
Emperor Overlords will be your greatest threat and can ruin an otherwise solid defense. Use your individual General’s Powers -- Cluster Mines, Carpet Bombing, Artillery Barrage and EMP Pulse -- to individually derail these threats.
Walkthrough
Basic Start: Build a Reactor, extra bulldozer, Barracks and Supply Center.
Important: Build two extra Supply Trucks. Super quick buildup is key. Build twin soldiers and set them on there way towards the oil rigs in the far south east corner. They will pull in an extra $3000 before the Tank General destroys them.
Build a War Factory and Propaganda Center before building any base protection.
Immediately crank out two Overlord Tanks. Upgrade them both with Gattling Cannons before building any other structures.
Station the first Overlord very slightly east of your base. Station the second Overlord at the northwest corner of your base. Hopefully your base is somewhat compact and not too many vehicles will have to be chased in the middle, northeast part of your base.
Almost immediately you will have the funds to build Speaker Towers behind both of your Overlords. These are true lifesavers. Make sure there is room within these Speaker Towers to place an Air Field.
Temporarily bring both tanks to the east to handle one onslaught of troops, then rush one of the tanks back to the northwest to again protect that area of the base.
Next build an Air Field and two MiG Fighters. They don’t pack that much punch, but they might keep the Emperors from attacking as soon.
Build another Overlord upgraded with a Gattling Cannon and station it at the northeast corner of your base. Back it up with a Speaker Tower.
There is no easy way to fight them off the assaulting Emperors. Go back to your previous save if you lose the battle. Use your General’s Powers to Carpet Bomb them, Cluster Mine them, Artillery Barrage them, attack them with your air units and, of course, your Overlords. Once you get the right combination, all three of your Overlords can survive this attack.
But there will be no rest. Immediately the air assault picks up. The Gattling Cannons on your Overlords can hold them off a few times, but it is necessary to build two land-based Gattling Cannons (as opposed to your Overlord upgrades) – one at the northeast corner of your base and one at the northwest corner.
Next it is time to build one more Reactor and then patiently wait for the funds to build your Nuclear Missile. You won’t have much leeway to get this done.
Build a third and fourth Gattling Cannon to help combat air units.
Your base is still not totally secure. Emperors will still approach your base, usually one at a time. Keep a lookout and use your MiGs to help damage the incoming Emperors.
Overall, put your MiG’s on Guard mode near the middle of your base to keep them away from Gattling Tanks. Have them in Guard mode for the air only when the air attacks begin.
Start building up your hackers before you totally run out of supplies. Once you have eight, build an Internet Center to house them.
Upgrade to Chain Guns at the War Factory as soon as possible. This will make both your Overlords much more powerful.
If you haven’t already, obtain Radar at the Command Center to help locate the enemy’s Nuclear Missile.
When your Nuclear Missile is ready to launch, be sure your Artillery Barrage is upgraded to level three and launch a dual strike to destroy it.
Actually, it is possible to destroy the Nuclear Missile with the Carpet Bomber and Artillery Barrage. If you destroy it in this manner, you can destroy the Propaganda Center with your Nuclear Missile to slow down the production of Emperor Tanks.
There is a side benefit to this. The bulldozer may be sidetracked to build the Propaganda Center instead of the Nuclear Missile and the Nuclear Missile may not be rebuilt again on this mission!
It is highly recommended to upgrade your MiGs with Technical Nukes at the Nuclear Missile. After this, your MiGs can literally flip an Emperor over. Very impressive.
Subliminal Messaging is also a nice upgrade once you have the funds. This will upgrade the protective powers of the Speaker Towers by 25 percent.
Offensive Operations:
From here on out, your base is fairly secure. Double up your defenses with Overlords, with your choice of upgrades.
Start building additional Overlords and Nuclear Missiles to assist in your offensive operations.
Once you send your Overlords go out, you will want a large number of Gattling Tanks to escort them to help protect them from air assaults.
The defense will be spirited at the Tank General’s base.
If enough Nuclear Missiles are built, it is possible to destroy the Command Center, then the bulldozers as they return to rebuild it. If all bulldozers are destroyed, you can then systematically destroy their base without any structures being rebuilt.
It is not necessary to destroy Speaker Towers, Bunkers and Gattling Cannons for the Tank General to surrender.
Mission accomplished!
HH Alternate Strategy
This level is actually quite easy with the right base defense.
Build two extra dozers for a total of three. With the first dozer, build a power plant, with the second, build a barracks on the backside of your command center. With the third, build a supply depot. When each dozer is finished with its first build, each one will construct a 'T' defense. This defense has a gatling cannon, with a bunker on either side and slightly behind, and then a speaker tower well behind. The structures make a T shape, and the top of the T (gatling cannon) should be pointed towards the attack.
Attacks come from the north, east and northeast. First build a gatling cannon in each of these three spots, the northeast one should be built southwest of the rocks, and the other two a similar distance from the command center. The gatling cannon is the top of the 'T'. The finished 'T' has two bunkers (the tips of the crossbar of the T) and a speaker tower (the bottom of the T), but start with one bunker in each position, and then start pumping out rocket men to fill the bunkers. Then build the second bunker on the northeast T defense, and then second bunks on the north and east defenses. Then fill those bunks with rocket men as well. Remember that each of these formations has a designated dozer.
Once this defense is up, it will hold for the entire game as long as you add speaker towers when you can, and make sure there is always a dozer in each one repairing. Now just build up the tech tree to a nuke. Later you can add the ECM tank to each 'T' defense, but for now pump out eight hackers and get your money set. Now its just a matter of building nukes.
If you find yourself losing too many dozers to the airstrikes, just build a bunch of decoy bunkers around the edge of the base, but make sure not to block the firing lines of the occupied ones.
Alternate Strategy
You may find that the initial strategy of building two Overlord tanks and an Airfield was not enough to fend off the initial round of attacks. It is difficult to build the airfield in time, and a group of 3 Battlemasters and 4 Gattling Tanks attack the northwest corner early on, overwhelming a single Overlord.
An alternate initial strategy is similar to above, except in a different order and with no airfield. Build 3 Overlord tanks (all with Gattling upgrades). Send two to the northwest corner, and one to the east. Build your base compact enough so you can position the Speaker Towers and Overlords so that your Overlord guard areas just barely overlap at the northeast corner. Ideal positions are at the southern edge of the patch of dirt north of your base, and the western edge of the patch of dirt east of your base.
Now, forget about the airfield. Build the Gattling Cannon upgrade from the War Factory. Then, build a single bunker close to your base, directly between the two Overlord groups if possible. Fill this bunker with 3 Tank Hunters (a Red Guard can also help defend against enemy Tank Hunters), adding more later when you have a chance. This bunker is critical to defending against enemies that come from the northeast. If it's positioned right, you'll find you can get through the entire mission without it taking a single bit of damage.
As soon as you have enough funds, build the Subliminal Messaging upgrade. This will allow your Overlords to heal faster. Begin building a 4th Overlord with a Gattling Upgrade as soon as possible.
When the first enemy Overlord attacks from the northeast, do not go out to greet him, or your Overlords will be outside of Speaker Tower range. Instead, lure him in, let him head towards a target, and move the other group of Overlords to him for support. After defeating him immediately return your Overlords to their original positions; two more enemy Overlords will arrive, one from the northwest and one from the east.
Once your 4th Overlord is complete, move him to the east Speaker Tower. If all has gone well you should now have 4 Overlords, a bunker full of Tank Hunters supporting your blind spot (as well as providing air defense), and the Gattling Cannon and Subliminal Messaging upgrades helping you out. At this point, you should have defeated the initial wave of attacks, and now have a few short seconds to catch your breath.
The next wave of attacks is fierce. Two Overlords will approach from the east. Do not allow your Overlords to leave the safety of the Speaker Tower. You may bring one of the northwest Overlords to the east to help defend. Expect to lose one or two of your tanks. If you lose more, funds will be tight; it would be better to restore from an earlier save point and try again.
Keep your two dozers near the Speaker Towers. The incoming attacks generally will not target them, and they will auto-repair your structures in the area.
After this, you will be given a moment's rest. You will be attacked with enemy Helixes and Battlemasters but they are easy work for your tanks. Build replacement Overlords if necessary during this time (you want 2 by each Tower), and start building hackers and tucking them safely in the far southwest corner of the map as funds permit. Build a Gattling canon just east of the northwest speaker tower to help fend off Helix attacks, build a Gattling canon just north of the eastern tower later on after you have some hackers. You can hold off on the Internet Center until after you've secured your base, but be sure to build hackers before your supply pile runs out. Once your supply trucks start heading for the supply piles at the northeast corner of your base, you can pretty much say goodbye to them. You'll want the Radar upgrade as well; it will help you keep an eye on your defenses.
You should have all 5 stars by now. You'll want level 3 artillery barrage, cluster mines, carpet bombs, and the EMP bomb. Drop cluster mines around your base every chance you get, they'll help break up incoming attacks. The repair upgrade can be handy to save your Overlords in a pinch.
You have two options to fend off the Nuclear Missile. The Nuclear Missile silo is built by a group of rocks at the dead center of the front edge of the enemy base (just north of the larger lake in the northeast corner of the map). Use the EMP bomb over the rock formation to clear the fog of war (the bomber will probably get destroyed) in this area and check the status of the missile and reveal nearby structures. If the opponent has not started building the missile yet, use your artillery barrage to destroy the Propaganda Center (just northeast of the rock formation). Keep doing this as soon as your barrage is available, and the missile silo will never be built at all! If the opponent has started building the missile, then fire the artillery barrage and carpet bombs at it to destroy it.
Your base defenses are not perfect, but are pretty good at this point. You have 4 ranked-up Overlords, 2 Speaker Towers, 2 Gattling Cannons, and a bunker full of Tank Hunters. You have a dozer at each tower keeping the towers and cannons in good repair, and a small group of hackers keeping the cash flowing. Take this opportunity to build up 8 hackers, a third dozer, and an Internet Center for the hackers. Build the Internet Center and new structures with the new dozer, keeping the first two dedicated to tower repair. There's no rush at this point, so build the Satellite Hack II if you want, it always comes in handy. Keep an eye on your Overlords, the most important thing to watch out for at this point is the tanks straying too far from the Speaker Towers.
Once you have the hackers set up, you will now want to build a second power plant and a Nuclear Missile. Now you're ready to go on the offensive. Stick to the same strategy as above; send in groups of Overlords and Gattling Tanks, with the Nuclear Missile for support. If your base is cramped, you may not have space inside your defenses for additional missiles. Most large tank attacks come from the east, to make space for nuclear missiles, build them to the north of your base, creating another Speaker Tower, 2 Overlords, a Gattling Cannon, and a Dozer group for defense. To increase cash flow, build some more hackers and hide them in the southwest corner.
From here on in, it's pretty much standard offensive tactics, although certainly no walk in the park. Nuking the opponent's Internet Center and hackers will significantly reduce the attacks. Inferno cannons can help you take out base defenses from a safe distance, but they're easy targets for air attacks. The Isotope Stability upgrade will help keep you from destroying yourself, although keeping an Overlord with a Speaker Tower in your forces can be just as effective. Watch out; attacking the opponent's base sometimes triggers a massive offensive attack, if your base defenses aren't prepared to handle 2-3 Overlords and large groups of Battlemasters then you may be back to square one. Beware enemy ECM cannons later on in the battle.
One offensive strategy is to send in groups of 6 Overlords at a time; 2 with each type of upgrade, with the bunker upgrades loaded with Tank Hunters. These provide great protection against all types of attacks. Approach from the west to avoid most of the incoming tanks, and use a nuclear missile to take out the base defenses at the west entrance to the base. Use another nuclear missile to take out the huge group of defensive tanks waiting around his war factory. As your group of 6 Overlords is working up there, build another identical group of 6 and send them in as reinforcements as soon as possible. Continue doing this and you will wear him down to surrender. Isotope Stability really helps here, as does rolling out your tanks over the fallout from your nuclear missile while blasting away at base structures. Take out his Internet Center first to make the job easier.
Here is a base layout with space for 2 nuclear missiles (there is one in the center, and room for another at the northwest). The eastern speaker tower is just off the right edge of the screen: