I've now played about 40 games on ICO, and almost every time my allies and opponents made some fundamental mistakes. I'm writing this guide in the hopes that some players will pick up my advice.1. Fleet comes first
You cannot win this game with a tiny fleet. Whatever you do, your first priority should be getting a fleet and ever increasing its strength. Use the relative fleet rank indicator near the bottom of the screen. Ideally, your fleet rank will be 1.2. Use Scouts
If it's not 1, it means somebody else has more fleet, meaning you quickly need to build more ships.
If your fleetrank is 1, then you have some room to do some research, but don't forget to still build more ships, else you will fall behind eventually.
You need to know what your enemy does. If you blindly spam Illuminators and attack the enemy and suddenly realize he has spammed Fighters, you have lost already. It means you did not scout, but your enemy did.3. Build counters
For example, if you see your enemy spams LRMs, Illuminators or Assailants, don't build light frigates, LRM's and such yourself. You need to build the appropriate counter unit: Strikecraft.4. Do not rely on a single shiptype
Every unit in this game has a counter. Since you do use Scouts, you know what your enemy does. React to it and build the required counter units.
If you only build one type of ships, your enemy will eventually show up with a fleet of counter units, totally obliterating your fleet.5. Expand aggressively towards your enemy
You need to expand towards your enemy so that you can put pressure on him quickly.6. Attack early, attack often
Ideally you want a planet right on your enemies doorsteps. At such a planet you build a couple of repair bays and frigate factories.
Don't worry much about juicy planets in your backwater you didn't colonize. You can always do that later with a smaller, second fleet. At the same time your primary fleet will keep the enemy very busy.
Start harrassing your enemy from your doorstep planet(s).7. Micromanage your fleet
During the time it takes him to move his fleet to the planet you attack, you can often destroy a couple of buildings.
If the odds are against you, you can easily retreat to your doorstep planet and quickly repair. But don't wait long, go attack again immediately, preferably on a different planet.
This applies especially to Illuminator spammers. Having 50 Illuminators at home does you no good. But having 50 Illuminators divided in 2-3 smaller fleets harassing your enemy does.
Save your antimatter, disable autocast of some abilities and use them more wisely manually. Manually order damaged ships or ships your enemy tries to focus fire upon to retreat, fly them once past your repair bays and let them return to the fight.8. Do not build static defenses
Static defenses are a total waste of credits and resources. First of all they cannot move. If you build turrets on planet A and your enemy attacks planet B, the credits and resources spend on A do no good on B. If you had put the credits into fleet instead, you could have had more ships.9. Know when to retreat and when not
In addition, fighters, bombers and at least Vasari Assailants (possible other races long range ships too) can take out turrets without turrets being able to fight back at all.
There are exceptions to this rule, but I'll let you figure out the situations in which turrets can be helpful on your own.
If a fight drags out and you are beginning to lose too many ships, you might have to retreat. However, retreating is not always a wise choice.10. Find ways to disable enemy phase jumping if he tries to flee
For example, never retreat if your enemy has a Phase Jump Inhibitor. While your ships spin up their jump drive, they'll be totally helpless and your enemy will destroy your ships one by one.
Likewise, do not retreat if your enemy has jump disabling abilities. For example Vasari can use Subverters and their colonizer capital (also called Space Egg or Space Whale) to prevent enemy ships in a quite big radius from jumping.
If you still have to retreat, take out the PJI or the jump preventing ships first. Alternatively, spread over a huge area, don't clump up your ships. Or sacrifice a few of your ships and only retread half of your fleet.
Whatever you do, if you flee in such situations, you will have heavy losses.
Turn the tide. If your enemy flees, prevent it. Be sure your choke point planets have a Phase Jump Inhibitor.11. Use the black market
I usually play Vasari and often have excess resources but lack of credits. So I have to sell my resources in the black market. There I almost always have put some resources for sale too. But for some reason no other player seems to buy them.11. Dear TEC players, forget about early trade ports
Especially TEC players should like the market I think, they should have excess credits and lack resources. So use the black market to your advantage.
Assign hotkeys to quickly buy and sell metal and crystal.
This mostly applies to smaller maps where you meet the enemy more sooner than later.12. Capture the neutral mines
Basically trade ports take too long to pay off, building them early on leaves you with just a small, vulnerable fleet and you might not survive long enough to enjoy the benefits of trade ports.
Neutral mines give a very nice resource boost. If you are Vasari you can use your Scout ships to capture them. If you're TEC or Advent, use a colonizer frigate.13. Learn from your mistakes and adept
Over the course of the game, check after your mines once in a while and recapture them should your enemy have stolen them from you.
Hopeless case, some people never learn