We've had a lot of demand for a strategy guide for the Mushroom Kingdom challenge mission. This is a particularly challenging mission.
A big part of the fun of this mission is to learn as you go along. Before you read any further, are you SURE you want to spoil it for yourself?
If so, here it is. Start with a turret next to your Capitol and a Skyscraper a bit to the northwest, along with a gold Extractor. We're going to sell the other Skyscraper in a moment -- the one that started on the map -- so make sure this Skyscraper also covers the gold Extractor and can keep it alive after we sell our original Skyscraper.
Here, we've now sold that Skyscraper, and built a crystal Extractor plus a new Skyscraper toward the northwest corner, right next to the mushroom.
Now we have 2 gold and 2 Crystal extractors, and we build a second Gun Turret and start upgrading our Skyscrapers.
We continue upgrading these two Skyscrapers and also build a Missile Launcher a bit west of our Capitol.
It's a good time to build a third Skyscraper -- only after our original two Skyscrapers are fully upgraded. We'll also want a Disruptor and another Gun Turret next to the Capitol. Note that we've also started building some Dropship Pads just to unlock the units, and to block off the southeast corner of our Capitol, which we won't need to defend as much.
Note that things will start to get fast and furious around this point. Don't hesitate to use the Bombardment mothership effect as needed on enemy troops as they arrive at your Capitol; you will likely need to use it several times throughout this mission just to stay alive.
We immediately work to upgrade that new Skyscraper while extending our base outward. Note that the CosmoKnight Dropship Pad just above our Capitol is a placeholder; we're going to sell it and put a Laser there once we feel comfortable spending that much money.
Also note how we're now building a lane to the west of our Capitol for our Laser to fire down.
However, we do have a bit of a problem; the shortest path for the enemy now takes them to the north side of our Capitol, so we'll need to block that off.
In this mission, which is so bone-crushingly difficult, it's very important to build Skyscrapers one at a time, and make sure they're fully upgraded before spending the 3 gold investment to make a new one. Also keep a close eye on your income vs your enemy's income by clicking on your Capitol as well as your enemy's; don't let yourself fall too far behind!
You also will very much need the flying repair craft that come with level 3 Skyscrapers.
Below, we've continued to expand our base, and built a Laser plus a Reflector (hidden behind the Skyscraper in the lower left). We've also built a Grenade Tosser just southwest of our Capitol building.
Note also that we've now added substantially to the defenses north of our Capitol, to help defend against the Gunships, which become quite deadly later on. At least for now, it's a good idea to build in a wide area with level-1 towers around your Capitol rather than focusing on upgrades at this point, since the enemy will use the Stun mothership effect as often as he can, and the only way to defend against that is to have a lot of towers spread out over a wider area than his Stun can cover.
Again, don't hesitate to Bombard as much as you need.
Now we expand a bit further, and build another Reflector to make sure the enemy comes within range of our Grenade Tosser twice.
Note that we prefer Gunships as offensive units in this map, since the mushroom forest just north of us limits the amount of aerial defenses the enemy can build. Note that we're building the Gunship Dropship Pads essentially as walls for now, but they will become a serious attack force once we upgrade them later on.
We've also built a Chiller Unit to slow the enemy at the corner.
We continue building Skyscrapers and upgrading them fully, and we also have now built 2 more Reflectors to turn the Laser's path, along with a second Grenade Tosser a bit to the west of the first one, just above the Chiller Unit.
We've let the last gold deposit -- the one farthest to the west -- sit idle all this time. Now we can finally build a Skyscraper near there, and upgrade it fully.
-We're starting to really turn the corner in the race for income, and we're building lots of Skyscrapers as walls now.
-We've built a fifth Reflector to turn the Laser beam again.
-We've built additional anti-air defenses north of our Capitol, including a Lightning Tower, which is extremely important for taking down the most heavily upgraded enemy Gunships.
-We've upgraded our Laser to level 2.
More Skyscrapers, more anti-air defenses ...
Note that when defending against air units, a mix of defenses is always best. Missile Launchers do great area damage, but can easily be overwhelmed if that's all you build. Lightning Towers are great against the enemy Gunships with the most health, but their slow fire time means they're wasted on Gunships that are already close to death. Gun Turrets, however, are excellent at taking out the weakest enemy Gunships so the other towers can focus on the high-value targets.
We've also now finally upgraded our Laser to level 3.
Did you notice that we didn't upgrade our Capitol this whole time? It may be worth doing at this point, but we chose to race for income instead. Here, we've build Skyscrapers like crazy and are furiously upgrading our Gunships and building anti-air defenses.
Finally, with some help from carefully-timed use of the Radar Sweep, Heal, and Stun effects, our Gunships are able to push through to victory.