Ok here is my Strategy for late-game win. works almost everytime.
Concept: Turret hug and use infantry for tank. Use special when needed to save or for income burst. Hold out until late game and then save for two Gods.
Early Game: Build an egg tower and up your infantry armour. Keep making infantry to keep the enemy out of range of your castle but within range of your turret. Try to upgrade money as soon as possible and 1 lvl each of turret atk/range. If units die easily, up armour too. Save for another tower slot and build an egg tower there(don't evolve yet because egg towers rape).
Mid: Try to save for another egg tower(3 in total) and then evolve whenever possible. Don't get rid of egg towers until the second to last evolution, where you get the double rocket launchers. You can get one of those until you evolve one last time.
Late Game: In the final evolution, keep using your infantry to tank and turret hug to gain income. Sell your egg towers for the better towers and buy max your tower slots. As with before, use special when necessary and max money, infantry armour, turret atk/range, and buy God upgrade. Once you can get two gods, send them at the same time with as many anti armours as you can make. Upgrade at least one lvl of the anti armours and use special to clear defenders.
If you do this right, it might take a while, but it will work on any mode.

Do you know how I played It was easy
I trained one melee fighter and two range fighters.these are cheap and give more gold and exp. with these first I upgraded range stuff.then I did that with the whole game.After I have enough I trained the big guy like dinosaur guy in place of melee

I found a weird glitch that no one else has mentioned. In the 4th and 5th ages, you have to unlock the anti-armor, right? Well, you can actually just make them without buying the upgrade at all. This ONLY works when the unlockable is the anti-armor. I have tested it out on multiple websites and all the difficulties.

I mostly make a lot of armor troops

1 melee + 2 ranged is a good strategy, but only on easy-normal modes. On hard it doesnot work...What about insane - i scare to play in it =))

This is not that tough to beat on Insane

1:  build a tower and egg turret
2:  Spam support units and make range upgrades when you can
3:  Continue to spam support units and make damage upgrades when you can
4:  sell you previous turret and keep upgrading to the best you can afford
5: max out damage and range for support units and keep spamming them.  I was able to beat it shortly after getting to a future tech level while the AI was still on modern.

Insane was not as bad as the original game, but you use a similar concept to beat it.  Stick with support units as you can get 4-6 units firing at once when you have your range upgraded and it will give you a good cost/unit destruction ratio that should keep you in the gold.  You can throw in some gold upgrades but I don't think it's really necessary.

AOW2 Is awesome... Can't Wait for a AOW3!!

Ok guys, YOU ARE ALL SIMPLY NOT CLEVER (LUCKY) ENOUGH, TO SEE THE SOLUTION, so ill help you :(

Insane difficulty:

1.) Upgrade 2x support range 1x support damage OR 2x support damage
2.) Wait until enemy reaches your base AND attacks it
3.) Spam support Units, the enemy keeps attacking the base.
4.) Now you have many support units on one point, the power when they are shooting at the same time is simply giant.
5.) Try to get as often as possible many support units on one point
6.) Youll get strong enough to spam tons of priests in the egyptian age, and they have the ability, to attack enemys base also when a enemy is standing in front of it, means your Victory!

Use your special only if you get killed otherwise.

Clear enough? No infantry, no anti-armor, no heavy, no turrets, and if your good no specials, kk? I was kinda the first who beat AOW on impossible and AOW2 on insane, and you know why? Cause i love calculators and calculating, kk? kk!

~ Quicky

AOW2 Is awesome... Can't Wait for a AOW3!!

Sry, but our dear Louissi said he wouldnt do a AOW3, but go to interactive pixels where he informs his fans about his next projects...

http://interactive-pixels.net/

I found the best strategy to be infantry, support, infantry, then support and so on until the last two ages (modern and future). It's much cheaper then the best unit (armor) and infantry followed  by support can do as much damage as an armor unit.