I’ve seen a few posts looking for help on the harder levels….So here are some things I have learned. I’m sure some will disagree with my approach and I’m sure there are multiple ways to win on suicidal, but this does work.
Once you have beaten suicidal once, it gets easier to do it again and this will allow you to drop the cheese you don’t like and try other alternatives. This is designed to be a primer that gets the player who can win on crippling a suicidal victory. The following works well for large and huge maps with nine players and stars/planets abundant.
Warning! This does contain cheese!
Second Warning! It’s looonnngggg.
Race Cheese.
Don’t build a custom race. Some of the pre-built races have "free" bonuses. The best example is the Drath. If you clear their stats, they have lots of bonuses even with 10 available points. Just clear the points and then add in areas where they don’t have any free bonuses.
Pick up some population growth bonuses. This will help out considerably with the money crunch and the colonization rush. I personally favor pop and economy with the points. The social and military production for the political party bonuses.
Set your relationships with other races to friendly. This will allow you to trade with them prior to meeting them.
I personally think tight cluster games are much harder (though more fun IMO) and should be avoided for your first suicidal.
First turns are critical…
The goal is to get enough industry set up that you can punch out a colony ship every one or two turns (depending on what factory level you can build and bonus tiles) while having military spending at ~50% within the first four or five turns of the game.
Industry and social 100%.
Stack four factories (I sometimes do more if I only have basic factories and no bonuses) in your build queue. Put a social and an econ at the end.
Until you have all your factories built:
Do NOT buy the first one in the list, buy the second factory. All of your production will go towards building the first factory in the list. If you buy the first one, you are spending less money on buying factories than is possible. By always buying the second factory you can actually get your four factories in less than four turns as a factory or two will be built by the natural build process.
I do NOT set morale to 100%. I need the cash too badly. This is where the race bonus pays off.
Flagship set to Auto-Survey.
Design a faster colony ship.
Around half your initial stockpile of money is gone. You will be living on the rest during colonization rush. Don’t try to get every last colony. Do try to not share planetary systems, it makes other races touchy, but don’t give up any good planets just to avoid this... Get every resource you can. I always switch to the second stage of the game slightly ahead of the computer. It makes the next stage easier, since the computer hasn’t moved on to ships and tech yet.
Get Xeno Labs, then Diplomacy. As soon as you can, trade, trade anything but Diplomacy techs. All research spending should be dedicated to Diplomacy for the early part of the game. The only exception to this is, if you are already too far behind, you may need to research something for the purpose of giving you an initial trade good. Sensors I & II are good for this since the computer will not research them and you can trade both to nine races…
Be the tech broker…Always trade to those who have the least and are the furthest from you first. Target diplomacy techs first. Sell bottom ends techs as necessary to get you over the financial hump. Wait until the last minute to do so. Since you are improving your diplomacy, the longer you wait, the more you will get. Look for morale and economy boosts so that you don’t have to get into selling useful techs for cash. Sometimes you will have to spend some research on morale/econ. Do NOT research weapons for the start and mid game. Trade for them. Wait until you need them (I mean you are going to do a ship design, not somebody has declared war on you!) to trade for them after you get past the first few techs. Since all preceding techs are free, you want to minimize the number of weapon trades.
Game flaw trading cheese!
You can trade Planetary Defense + Planetary Invasion for less than Planetary Invasion alone.
Some Cheese!
Look for an early victim. Inevitably one of your neighbors will not do a good job of building up a starting military. Jump him. Feel free to make peace willy nilly and then to declare war again. After the first war they will be touchy, and a second war will be inevitable. Get there first, and jump him again! There are diminishing returns on making peace. In this first war, you will need to run through a couple of games to get a feel for what you can get away with. This is the hardest victory of the game. Rinse and repeat until they are down to a planet or two and let the computer players fight over the last of the carcass (they will often make themselves vulnerable in doing so). There is no "tendency to conquer" diplomacy penalty if you do not militarily conquer the last planet. If your diplomacy is high enough and you have the bizarre, sometimes the computer player will give you his last planet in return for peace! This fixes the problem of having less planets than the computer and puts you on even footing.
More cheese! -
Now push for the bizarre (combined with good diplomacy, you can make ridiculous trades) and spin control. The bizarre gets you more when you make peace with the computer! Computer says you are too strong and will not trade with you for weapons? Empty out your spin control planet, end turn, trade weapons, dump your ships back onto your planet.
Second war -
The Drengin and Yor are your best friends, even if they hate you. With you having spin control, they will look elsewhere for victims. They will start wars with other computer players, both computer players will send all their ships out of their territories making their home worlds vulnerable. Set up your ships just outside of the area that will cause the computer to be alarmed. Jump the player the Drengin/Yor are at war with and make peace almost immediately. Rinse and repeat as above. Then let the Drengin/Yor do it all over again with another race. If they are getting too overwhelmed or you can’t get to the other party to the war, you may have to jump the Drengin/Yor and be down to one decoy race.

I have had games on suicidal where I wasn’t producing enough people with the 70% pop bonus because of this, even conquering a planet with a single transport…
If you are unlucky enough to not be able to do this with the Drengin/Yor, simply repeat the first war by picking on your weakest neighbor. With enough weapons trading, there is usually an obvious victim or two.
On the home front…
Morale is money. Move your research over to here as soon as your diplomatic advantage is working well. Seek out all the morale bonuses. At first use them to get up your tax rate so that you can reach a break even state and stop trading tech for cash. Once you are doing this, use any extra cash to toggle up to 100% morale for a few turns, to get the pop bonus and then toggle back down as needed to keep from going broke. You will eventually be able to simply toggle up and leave it there. Aphrodisiac and econ bonuses should start to be a priority as well.
At some point in the mid/late game you will have to start doing your own weapons research, or target computer players for invasion that have better weapons tech, but have yet to build up their fleets with it….But this is usually about the stage where the game turns into a mop up operation.
On war…
Faster is better. The computer simply doesn’t know how to address fast ships.
Redesign your ships anytime you get better tech.
The first war is usually small or medium ships. After that, I am almost exclusively large ships. They seem to be the ideal firepower/build time balance.
Bring all your ship to a rally point(s). Get your fleets put together. Do not combine troop ships with war ships. Put two fleets on the same square to defend your transports. When getting ready to attack, move all your fleets to the point where they are outside the computers alarm zone, but they will all take the same amount of turns to reach their attack destination. Move all the ships in at the same time (after the first war, this should only be one turn) until they reach their attack point. End turn. Attack with all ships, taking a crippling amount of the computers empire and make peace in the same turn or a very small number or turns (first war is multiple turns).
That’s it. You win!
Edit: I forgot! Always put those constructors next to other peoples resources. You will get to snag some for free. In particular, other peoples wars are an alert to stage them.
And one more, watch the charts. When the computer starts building military. You start.