.Mission 4: Arcadia City
For this mission, co-op is preferable simply because it is very hard to multi-task in this level, and this level requires alot of it. However, in solo, you get four hornets instead of two.
The first thing you should do is turn on the skulls that make the game easier. DO NOT turn on boomstick, because sometimes they will send engineers directly to your transports and if they just so happen to be the 5% that blow up, you lose that transport instantly.
Now when they ask you to clear the subway, take your hornets in and make them do all of the work. Send Forge around the map to gather supplies. You will need plenty because you will need to be able to build up your base as fast as possible when the time comes. Once you have cleared the subway, send the hornets directly to cargo one. Ignore cargo 3 because it dies no matter what you do.
Your main threats in this level will be Assault Beam Hunters, Locusts, and Sacrifice Banshees. Your hornets can normally make short work of Hunters and Locusts. Try to use the healing circles sparingly and only when the hornets really need it. Again, you want to reserve most of your resources for your base. Have forge wait by the grassy base spawn so you can build there as soon as Cargo 3 decides to kill itself. The other base is much too dangerous to protect since it is very close to the enemy base. Once your base finishes building, there should be just about 15:00 left until the EVAC. Build two supply pads, then a reactor to quickly get resources incoming. Expand your base to a station, and make another reactor. Upgrade to heavy supply pads as soon as possible, then make a vehicle depot. Then upgrade to a fortress and make another supply pad, and a field armory. Keep checking on cargo one because it frequently takes fire. At this point most of your hornets should have one star, which makes them much more valuable in battle. If you happen to lose forge in battle, and he comes back as a foot soldier, put him in the tower next to cargo one. He will not fight while he is in it, but he will draw alot of fire before he dies, which buys you valuable time to counter attack any incoming forces. Once you have enough resources, upgrade one reactor and pump out two wolverines. This will become the most valuable unit later in the game once they start to bring sacrifice banshees. Park them near the tail of the cargo ship and they will attack any banshees that threaten the cargo. Also use them to destroy vampires, since your hornets are highly succeptible to them. Make sure to fully upgrade the wolverines, since single launchers isn't enough to quickly take down a group of banshees. Many times, if you are lucky, the wolverines will take the hit of the banshee's sacrifice instead of the cargo ship. At the field armory, purchase Reserves, and recycle the building to make room for an Air Pad.
Now there should be about 5 or less minutes left in the game. Pump out more wolverines, preferably to have about four or five guarding cargo one, and get wingmen for the hornets. If you still have the hornets, they should have two stars by now. Many times assault hunters will ignore your defenses and head straight for the cargo ship. If this happens, use a carpet bomb and try to get your hornets to finish them off as quickly as possible. They can take down a cargo ship fairly easily if left unattended. Keep pumping out more wolverines and hornets to defend the cargo ship and when there is about one minute left, a large mega turret will come online and wreck everything. I tried to destroy it with any forces I had and I got destroyed every time. So the best thing to do is hope it doesn't hit your cargo ship for the remaining time, and you will win.