My main Homeworlds page
This page is about Homeworlds strategy at a very general level. I also have a page about tactics that discusses more specific scenarios and what to do in them.
Homeworlds is a game where it's easy to charge ahead with your own plans while ignoring what your opponent is up to until it's too late. That's why most of the tips above focus on making sure you look at what your opponent is working on. Choosing a goal and taking little steps toward it is often easy. Figuring out your opponent's plan takes work.
Before you start thinking about what you want to do next, identify what objective(s) your opponent was trying to accomplish with their previous turn.
Moves can be multi-purpose. Even after you see one purpose to your opponent's move, check for others.
Every strategy guide will warn you about building the last medium or small piece.
That's probably a bad thing if you won't be able to build that larger size as well. But some new players are much too afraid of taking the "last serving." Look ahead another turn or two. Figure out what would happen if you and your opponent both kept trying to build that same color.
It's not only building that can open up choices for your opponent. Here are all of the ways that you might be handing your opponent an opportunity to build.
The American Confederate general Nathan Forrest is credited with summarizing military strategy as, "Get there first with the most." This is a useful principle in Homeworlds. If you already control a system, then you got there first. If your opponent initiates a direct assault on that system, you will get the first opportunity to capture ships. To successfully counteract that first-capture advantage, your opponent will need to bring more resources to bear than you can (a bigger ship or yellow and red sacrifices). If you were there first and you also have "the most," then your system is impervious to direct assault.
So you just need to watch out for catastrophes...
One of the strategic tips in any Homeworlds strategy guide is, "When your opponent gets red, get red yourself." This is good advice. It often doesn't even matter much where the red ships are. If your opponent has a red ship anywhere, you need to get one anywhere that you can. Otherwise, your opponent can move any ship to a system where you have ships and you won't be able to capture it (unless the star is red). Your opponent will then be able to capture your ship(s) by sacrificing their red ship.
A single red ship can simultaneously deter invasions at all of your systems. Regardless of which system your opponent chooses to invade, you can sacrifice the red ship and capture the invading ship. Consequently, your opponent may choose not to attempt any invasions. I call this the "deterrent principle."
Similarly, if your opponent lacks red, your red ship can be used to power an invasion of any of their systems.
A single red ship can deter attacks for quite a while, but remember that a single red ship can only be sacrificed once. If your opponent launches an invasion that forces you to sacrifice your only red ship, then you don't have a red ship anymore. You may now be vulnerable to a second invasion where your opponent has red ships to sacrifice but you do not. If that invasion is at your homeworld, you're likely to lose the game.
The short answer is yes. If there's an overpopulation on the board at the end of your turn, it's usually because you deliberately created the overpopulation so that you could cause the catastrophe. Very rarely, you may be tempted to not call catastrophe when you cause an overpopulation as a side effect of some other action. But I'm here to tell you that you should probably trigger that catastrophe anyway. A good explanation turns out to be pretty long, so I've made a separate page for it here.
If you have a material advantage, you should be willing to cause catastrophes or force mutual sacrifices that trim down both fleets by similar amounts. A one-ship advantage is a bigger deal when both fleets are small than when they are large.
Contrariwise, when you have a material disadvantage, you should build ships and not worry too much if your opponent builds the same amount. A one-ship disadvantage shrinks (proportionately) if both fleets grow at the same rate.
If you have more large ships than your opponent, try to harass colonies before they have time to get another large ship. Move that big ship into an enemy system with lots of smaller ships and no big ship defending. Attack any ships that don't manage to escape. Be careful of catastrophes, which are often the best defense against larger ships.
If you have a large-ship disadvantage, spread your fleet out. A lone ship that can run away is an unattractive target for an invading large. Ideally, every ship should be be either
Here are BAD situations, roughly in order from worst to least-worst. I need to avoid these things (unless I can make something even worse happen to my opponent). Contrariwise, it's good if my opponent has one of these problems.
As the Homeworlds rules say,
"One of the easiest ways to lose this game is
to mount an attack that fails to annihilate your
opponent, but leaves your own empire vulnerable.
This most often happens when you knock out half
of a player's Homeworld, leaving you with fewer
ships and your opponent with a better-connected
Homeworld than before. Plan for total victory!"
This is good advice, and I'd like to add some details. The act of destroying one of your opponent's homestars has three destabilizing effects on the game, each of which can open new opportunities for your opponent to suddenly ruin your plan.
Destroying one of your opponent's stars usually costs you at least three ships. A two turn demolition can be achieved with three small star-colored ships and a y2--if you're lucky enough to have all three small ships of the star's color. Otherwise, you'll be destroying two or more of your own mediums and/or at least one large (more on what ship size combinations can be used to destroy stars here). In many games, that much ship destruction is enough to turn the balance of material power in your opponent's favor.
After a star's destruction, your opponent's home is connected to systems with stars of the destroyed star's size (the hyperspace bypass principle). If that star was a size that is in your own home, your homes are now connected (assuming that the universe was originally large). Having connected homes may give your opponent a chance to counter-attack.
The bank now has the pieces involved in your catastrophe, the stars of any systems that you abandoned, and your sacrificed ship (if you used one). Your opponent may be able to trade or build the pieces that you just returned. If you were barely containing your opponent's advances before, then the new ships might be just what they need to get back in the game. This is especially true if your move returned a y3 piece to the bank. A new y3 ship might give your opponent the mobility they need to give you trouble.
Destroying a homestar can throw a game into chaos in the ways listed above, and you should minimize the length of the chaotic period by destroying the second star as quickly as possible. If your plan to demolish the second star requires you to build more ships or to move ships to different systems, try to perform these preparation moves before destroying the first star.