Sorian AI builds its base defenses in a very efficient manner. It seems to build defenses in such a way to ensure perfect coverage 360 degrees around the base, and this coverage is for both land and air, with point defenses, artillery and tactical missiles. This is very different from the way most players play. I, for one, do not like immobile defenses, instead I prefer mobile shields, flack artillery, Persivals...

My question is why does it play like this? Is this how everyone is supposed to play, essentially turtling (a lot of feedback and observation tells me base defenses should only be built if necessary)? Did the developer fail to create a reasonable AI, so instead settled with stronger base defenses? Or does the AI calculate that those strong base defenses are the best approach?

It's one of the limitations with the AI. I've found that the Rush AI builds a lot less turrets, and a lot more tanks (though it will still build shields, TMD, and AA).

If you really want to see the AI go buck wild with the defenses, try the following:

-Unit cap 2000
-No Sea
-No Air
-No Game Enders
-No experimentals

How long are you waiting for that to happen?

Also, if the computer has no air, and no sea, OF COURSE it's going to build lots of defences. You're giving it very little bloody option, save for spamming tanks.

Turn off all the limits, go play a 10km map with a lot of Rush AI. Short of playing real people, it's the most adrenaline filled game of FA you can have.

that's what a fortress ai will always do

I find the difficulty of the game is proportional to how much mass (and energy) is available in a level. On a small 10x10 map with very few MEXs per base (and directly in the base), and very little debris to reclaim, the AI is almost crippled if you take out even one of his MEXs, or deny him one of the bonus MEXs lying around.

Conversely, on a level like Seton's Clutch, sending a raiding party to take out a dozen of his MEXs seems to have absolutely no impact on his economy. Furthermore, the AI builds far more defenses in this case.

I'd have to agree with you on this one. I don't like using just the normal AI (Sorian AI) b/c it builds that 3x3 matrix of tactical missile launcher/defense, PD, AA, and T2 artillery.

Au contraire, I find that on maps smaller than 20km (where arty can still reach you) vanilla aix turtle is a mother******. I have yet to beat it.

My advice is thus: Shields. As many as you can imagine.