there is a much easier way

(at least this is how i got it, they may have rectified it since)

put the 4 AI on Easy at the beginning of the game, build up a big fleet or 3, then when uve researched everything and fortified your frontline worlds, save, exit, then load the game again and before you click start, set all 4 ai to hard or unfair whatever. then load and wipe them out

thing is the AI only builds at the beginning of the game. you could give the AI a few days to build up defenses etc... he might build a fleet, but thats about it. so within the hour or 2 (on the outside) that it might take you to wipe them out, they wont be much of a challenge.

thats just the easy way to get the achievement, but if you want a challenge, the above post also works

hm >.>  

4 hard ai's = easy actually

pick the smallest 5 player map u can find

put all the 4 ai's in hard mode,  and, lock the teams and put them in team 2,3,4,5 (you being 1)

build up like usual,  but don wait for the ai's to finish eachtoher then come to you.

if you'r stil having trouble you might wanna play online a bit, and host "comp stomps"  and learn from others there

It's a lot easier to just ally with one of the AI's. Do a simple mission or two at the beginning, give them some resources, or kill a few of the people they hate. It's a PITA, but it works well. The mission screen will aslo tell you how much 'favor' you'll get for any particular mission, so if you are well liked, you can skip one or two.

The real problem with AI's, is that once you're down to you and one, it doesn't matter how much they like you, they'll declare war on you.

lock teams, be deffensive at beginning, expand in ways to have lowest possible number of frontlines, make weapon techs and prepare big army... and u can get 10 hard AIs with no problem

like i said, start the game with all your AI's on easy, then when you've got a big bombad fleet, save, exit, reload with all AI as hard or unfair, and go for it.

best thing too, is that if you havent got any of the preeeding achievements like beat 1 hard ai by yourself, beat 2 etc (like i hadnt) you get them all shotgun, yeehah

If you want, play vinalla sins, it prevents it from building starbases, or a better way is to mod your race and then have your other 4 raaces not the same races as yours and then you can win with ease.

Shrug, I can't see it as being real hard. It might take a while - but it's entirely do-able.

The AI's problem is that it's too predictable.

1) Expand early to get what you can, until early borders become clear

2) Build a lot of defenses on your front lines. Always include a PJI

3) Move your fleet(s) to a system BEHIND your frontline gravwells. Hopefully there's a place where they can cover more than one frontline gravwell.

4) The AI will typically jump in with enough to take the system's defenses - NOT enough to fight both it and your fleet. Let them take a little damage (a.k.a. "commit" to taking your system, not waiting at the edge where they can jump out quick). This also gives you time to jump your fleet two or even four systems (depending) before their attack really starts hurting you.

5) Jump in (Group Jump) and head a course to where they will probably try to exit. Kill them along the way, then demolish them while they're held up by your PJI (plus not fighting back). Of course, anything that further pins them there helps even more.

6) If things go well, they just lost the fleet that was defending THEIR next system. So jump to it. Their fleet remnants will flee and you'll get their system. Usually. Not always.

This is a slow but pretty sure way to win. By the time they start having monster fleets, you will probably have a monster fleet and defensive frontline systems, too.

You win.