1 PLAYER MODE
You might think that there can't be any strategy for Massive Assault but there is mostly it depends on the map. I'll give you just the basic strategy. Its the same for both armies. I'll be giving it from the Phantom League.
There are two subsections for 1 player strategy:
2. Sleep then Assault
3. Defender (only when under attack)
Both are effective.
In assault as you start, attack the smallest country near you best with several smallfoots
and several cannons (always forget how they are called).
Here is how many of each should be bought, depending on starting money:
Cash Smallfoots Cannons DustTurrets
$8 2 3 0
$12 4 4 0
$18 6 4 1
and 2 bio-tanks
The smallfoots should be placed in the front
line, the cannons behind them and, the turret should be placed in the center of the base and the tanks should be placed either by the turret or on the sides of the turret line.(the same is done with your second opened allie
Then you attack. The smallfoots should attack the computer smallfoots and the cannons should attack the other cannons (at least one cannon should be shooting at the enemy smallfoots). The tanks,if near the turret, go to the battle only if you really need them. But, if near the battle, send them forward and take up the empty spaces which are left after your smallfoots where destroyed. At base build only bio-tanks and send them to battle. Or if the battle is won send them to another place where an enemy has opened or to the place which you intend to capture next. to Capture the next territory, built tanks, tanks and tanks and one rocketlauncher and one or if the territory is really big two Ostriches.
That was for a land mostly map.
Now for a water mostly and island map:
For This type of map build maximum firestorms and spend the rest on killer whales. Keep them near your base for protection. Then try to build a bit more of killer whales, The rest of the money should be spent on two transports and lots of tanks.
When the Turtle transports are full, build several tanks to guard your base and buy three planes( if you cant buy three dont worry, just buy the rest on the next 2 or 3 turnes). Send your ships forward and attack the enemy ships, try to get them in a small territory with their little ships in the back
and their battleships in the front, while you yourself are in a more wide territory with you killer whales in the front and your firestorms in the back. While the enemy is busy fighting with you somewere unload your tanks on their territory take out rocket launchers and if they have ostriches. and take thier base. The same should be done with the other computer territories.
SlEEP THEN ASSAULT
Open your richest territories.
As you start, build tanks, as much of them as you can. Then build a land transport, 3 rocket launchers, turrets at your territories borders. And then more tanks.
Send your army to the computers main territory on the way conquering neutral and secret allie territories.when you conquer the first territory build several tanks to fill up your army. Build several lets say 4 ostriches and a rocket launcher. And continue conquering enemy territory, building more and more tanks.
defender should be used when an enemy attacks you.
Build a tower in the middle of your base leave some space around it, on the second line of circles (push ctrl) put tanks. on the first line you should put cannons facing the way from which the enemy is attacking.
Try to get your army as close to that position as you can if you dont have a lot of money then don't build the cannons (mortyers, did i spell it right?) and put the tanks in their place. Now just enjoy defending.
2 PLAYER MODE
Sorry but i'm kind of tired typing this so I'll give you just the basic hint.
Its all the same, just remember that you know where your enemy is and he knows where you are, and also remember: people are smarter then computers.