I'm not really qualified to advise because I've never tried 1v3 on Hard successfully. But I do have a question: how many turrets are you building?

Enemy AI attacks can be repulsed extremely effectively by parking your defending fleet in a mass of turrets and a hangar (if Advent) that are covered by a regeneration building. If you survive to get a phase disruptor built, and you're playing a race that can further disrupt jumps (e.g. Vasari's colony capship Gravity Warhead), you can make them pay heavily if/when they retreat.

-- Retro

Try doing a map with different star systems, simply so you wont all of them down your throat at the very beginning.

I can say that I've defeated the max amount of AIs on hard before but it took hours. It's hard to say what you need to do though.

In the more recent builds, I can take on maybe 3 or 4 locked alliance unfairs at a time. But AI's are very different from human players (most of the time...). AI's don't have variable strategies. Sure, you might lose to them once or twice, but once you get the hang of how they operate, it's smooth sailing.

Also, it's quite easy to beat the early bounty. I don't know why, but maybe it's because allied AIs don't help each other out. That bounty is quite vital though. It's basically a second fleet for you that isn't blowing your planets up. Always try and win it.

Hmm... what else. Oh yeah, AIs have this weird 1 minute lag when starting. Use that nice buffer time to rush someone if you can.

I guess I'll just list down anything else that's noteworthy:
1. AI seem to be much more afraid of attacking than most human players. In fact, it's possible to defend fringe worlds with one or two turrets via the following strategy; build 2 turrets at planet. Enemy raiding fleet comes, start building another turret. Replace any destroyed turrets as they are destroyed. Of course, you have to adapt this strategy as you see fit, but it usually works quite well (a bit tedious when you are being attacked at 11 different planets at once).
2. The entire purpose of defensive structures in this game is to buy time for a fleet to arrive or stall the enemy long enough so you can attack. Don't ever expect your defenses to destroy enemy fleets for you.
3. A turret is more or less the same cost as a light frigate except with crystals. It also has much more health, armor, and damage. If you want to defend a planet, don't build light frigates en masse before sending them there, build turrets. A large mass of disorganized ships aren't going to win you any battles and is just going to waste your money. A few turrets can keep the enemy busy long enough for your main fleet to smash his planets. (This only works against AI)
4. The AI's early raiding fleets usually have no way to bomb your planets (composed of a few light frigates) so for the first half an hour or so, if you avoid building any major installations at your outlying planets, you can save a lot of trouble as those raiding fleets won't be able to do anything (except maybe blow up your extractors).
5. Chokepoints are important. Get them. Make sure you can defend them. I recommend building one repair, 2 hangars, and as many turrets as possible at chokepoints, but it really is up to you. The reason isn't to defeat enemy fleets, but merely to make the AI afraid of attacking (put fighters in the hangars).
6. Repair stations are a godsend. The AI doesn't really target them but they can really save you. Try to get them and hangars as soon as possible.
7. You might have noticed, but the AI doesn't really try to get those independent extractors that are in gas giants, asteroid fields, and the like. If your map has lots of those, rush for them. They're well worth it because they don't have upkeep like planets do, and the AI will almost never try to get them.

That's all I can think of really.

That's interesting, I sort of assumed that they had to be on a locked team. Mainly because I'd won several free-for-alls without getting the "beat 2 AIs" acheivement. But in retrospect, I generally did enough diplomacy to get an alliance, and didn't break it.

- Gus

I too have gotten achievements vs. Hard AIs in a free-for-all; they definitely don't need to be teamed. I know you can't be allied with them at the end, but I'm not 100% sure about alliances mid-game. Can you confirm this? If so, it would make this tons easier.

I've played through a couple more games.

On a Huge map (Aerolian Sector, 10 players, 6 stars, 67 planets), with 4 of the players set to Hard and 5 set to Normal, I won but did not get the achievement. I had cease fires with other players, but never a peace treaty. I tried to go to war with everyone moments before executing any kill, but screwed up on the 2nd to last Hard player. Actually, I don't know how that player died, since he still had planets. In any case, I didn't get either the 3 or 4 AI achievements.

On a Medium map (Dopplegangers), I beat 3 AIs who weren't allied with each other. I deliberately avoided any diplomacy at all because of the previous game, and when I won I got the "Comp Stomper" (beat 3 Hard AIs by yourself) achievement. Despite the fact that they were not allied at game start, it felt like they were, since all 3 empires sent wave after wave of fleets to my star to conquer me instead of going after each other. I'd gone for a very early Returning Armada and 2-3 phase portals per planet, so I managed to turn them back. Eventually I ended up with 2 very large fleets, one for home defense and one attacking fleet.

Prozack2k3 claims you can make temporary alliances so long as you're at war with everyone when you make the kills. I have yet to confirm this or disprove it, since I flubbed that. I did establish, though, that it's not enough to win the game without an ally at the end.

- Gus

I wonder how they define "leading." If you decide to go for economic boom with the TEC instead, and deliberately keep a relatively small military, do you think they'd still gang up on you?

- Gus

a decent RA tactic would kill the AI

I find it is ALWAYS best to nab all those asteroids outside the chokepoints. Why? they act as an early warning system. With the tecs phase jump detection research you can see enemy jumps up to 2 jumps away. with a planet outside the chokepoint you can now see enemy movements 3 jumps away. Giving your defending fleets more time to react to a possible assault. Nab these outlying planets. Upgrade pop just enough so you dont bleed cash and dont spend any more on them...Also an invading fleet will stop to take the planet giving you even more time to bolster your defenses

Tactical defenses, (very important) make allainces against the biggest faction, second biggest if its you, multiple, diverse fleets(no LRM/Flak spams)

Sigh, I had this whole long list of tips, but the forums ate it. Sooo not typing that out again.

Short version:

Even when locked together, comps don't actually work as a team. Use this understanding to help gauge what is defensible and what is vulnerable.

Expand early, as much as you possibly can. Get 10-15 frigates with a colony cap and just take every planet you can, in more than one star system if possible. Don't expect to keep them all, just cancel out the underdevelopment tax and keep the ones that can be easily defended with a few turrets. Build 2-3 colony/scout frigates and cap every neutral extractor you can manage. They are huge in the early game econ and NPCs generally ignore them. Use the crap out of culture. Aside from the obvious econ and combat bonuses, this is a key mitigation in how quickly you can actually lose planets. Even when you don't have a colony in one that was recently attacked, you still essentially control it.

Don't think you have to save every planet that gets hit. There will be some degree of 'musical chairs' going on with your systems for much of the late game. You just need to be hurting your enemies faster than they're hurting you. Try to cripple one enemy faction at a time. Since they can't unlearn the fleet caps, their econ is quite vulnerable later on.

One/some of the previous posters were right about orbital defenses. They are essentially a time ablative. Use a lot of turrets and some repair bays to keep an enemy army stuck fighting structures as long as possible.

Use heavy cruiser based fleets for def, 2-3 caps that support cruisers and can prevent jumping. Def is a breeze with Vasari as you can use jump ports in every system. Use bomber carrier based fleets for offense, with caps that support bombers and have colonize/defense mechanisms. Bombers require way less babysitting for the tedious structure killing, and can do their jobs from an easily escapable position in the gravity well.

Bottlenecks are not required, though I think that large maps are a lot more viable than small ones. You will not win this quickly, barring any strangely effective rush techniques I don't know about. I have a lot more information, as fighting multiple comps vs me is basically how I play the game for fun. PM if you want more detailed information.

edit: difficulty in winning this, I would wager, is easiest with Vasari, (1 jump to anywhere in defense, gravity bomb and subverters to trap) easy with Advent, (Malice + Cleansing Brilliance = bye crappy NPC fleet) and moderately difficult with TEC.