Babamots' Homeworlds Tactics Guide

My main Homeworlds page

This page is about what to do in some specific Homeworlds situations. I also have a page about strategy at a more general level.

Choosing your homeworld

Homeworld colors

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You should always start with green (either as a homestar or starting ship). Otherwise, you'll never be able to build a ship and you can't win. Sure you could start with red, yellow, and blue and then trade your ship to a green, but you may as well have started with a green ship.

You should almost certainly start with blue. Blue at home makes it easier to get ships in a variety of colors, but you could technically discover a blue system after a couple of moves and get your color variety from there.

Most players pick a large green as their first ship (hoping to sacrifice it at some point to beat their opponent at getting more large ships). That means they want one homestar to be blue, so the first color question they face is: should the other star be yellow (what Andy calls the "quick start") or red ("planetary defense system")?

I don't think that getting to move a ship out of your home one turn earlier is the real reason to pick a yellow star. Instead, having a yellow star makes it more difficult to destroy your home by star demolition. Demolishing a yellow star with a Doomsday machine requires a big yellow-economy advantage. Consider what it takes to make a 2b/2y Doomsday machine against a yellow-blue home:

One yellow piece is the target homestar, so the 2b/2y Doomsday machine must have 5 of the other 8 yellow pieces as ships. If the defender can get 4 yellow pieces as ships or stars, the 5 yellows needed for the Doomsday machine won't be available. Of course, the attacker might try to rebuild their sacrificed y2 after the blue stage...

One advantage of having a red star in your home is easy to understand: you can capture a lone invader as long as you have a large ship. Another advantage is that your red star is almost impervious to three-turn Doomsday machines (see below). But to me, the biggest advantage of a red homestar is that it is not yellow. By not having a yellow star in your home, it is easier to produce yellow ships in your home, and I consider yellow the most important economy to keep strong.

Homeworld sizes

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The homeworld size options are named here.

The banker setup is named for the investments that you can make by simply moving a green ship out of your home. In my games, investment systems usually get invaded before they can be cashed in, but it does seem like bankers successfully invest the most often.

As you read the game rules for the first time, you may think that the Goldilocks home setup offers some of the advantages of the banker and fortress. I haven't found this to be true. Except for a strange late-game situation, I've never seen anyone deliberately invest in a medium star, so I'd say Goldilocks does not provide better investment opportunities than the fortress. Although the supply of medium pieces may run out, I don't recall any games where a Goldilocks system was difficult to reach because of a low medium-supply. I think of the name "Goldilocks" referring to the simple fact that the connected stars are medium: not big and not small (like Baby Bear's chair).

To me, the important aspect of Goldilocks systems comes toward the end of the early game when medium ships are starting to come into play. You can accelerate the economy of your choosing by discovering medium stars of that color and getting access to large ships more quickly.

The strategy guides published by Looney Labs say that the fortress is hard to invade. I have played a few long games where the lack of small stars played an important role, but from what I've seen, the fortress has a more important role on the early game. Fortresses are the only homeworlds that do not have the "small star problem" described later. Fortresses also make it easy to jump-start an economy of your choosing by discovering small stars of that color.

Gemini homeworlds can make the universe small or even connect the homeworlds. For this reason, games with a Gemini homeworld tend to be somewhat shorter than large-universe games. The player who moves first gets a head start on building, and short games give the second player less time to catch up. Theoretically, short games should tend to be better for the first player (I don't have data to back this up, but it's what makes sense). Since Gemini homeworlds can shorten the game, they seem to be good for the first player and bad for the second. As I'm writing in early 2021, the player Draw5PlayAll on SDG has had very good success defending the top spot on the SDG ladder by starting with a Gemini system (they have been lucky enough to have the first move four games in a row!).

The small star problem

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Any time that you include a small star in your homeworld, the economy of that star's color gets a little head start: you've removed a small piece of that color, so medium ships of that color may be built sooner. Because of the danger of overpopulation, it is a little more difficult to participate in the economies corresponding to your homestar colors. Thus, small stars give a little boost to an economy where you have a disadvantage (possibly leading to a ship size advantage for your opponent).

In particular, if you are going second and your opponent chose a small star, you probably shouldn't have a small star of the same color (unless you're attempting an Instafreeze). They can get the last small of that color as a ship and freeze you out.

Instafreeze

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This is a trap you can set for new players when you move second.

If your opponent chooses a small star that is blue or green, (or maybe even yellow) you also choose a small star and first ship of that color. You can build the last small piece of that color as a ship and freeze them out of that color (see below).


All of the small blue pieces are in play. Players usually trade their small ships to get new technologies, but Alpha will have to trade their large ship to get blue.

New players won't notice the problem and you can build mediums and larges of that color before they know what hit them.

Experienced players will respond by trading their initial (large) ship to enter the economy and the position will be about even.

Your third turn

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On your first turn, you make your homeworld.

On your second turn, you build a small ship (there's almost never another reasonable choice).

On your third turn, you should consider trading your small ship for another color. If there are any small homestars in the game, then the medium ships of that color will be available for building soon. New players often simply build a third ship of their original ship color on their third turn, even when their opponent is poised to seize a monopoly (often over the blue ships). Don't get left behind! Identify the color(s) that will be open to building mediums soonest and get involved in that economy early.

Slow Doomsday machines

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Inevitable doom can last more than a day.

Destroying a homeworld by star demolition requires two catastrophes, and the defender will try to prevent each of them. The most obvious way to circumvent any possible defense is to create each overpopulation all in one turn. The all-at-once technique is achieved with the traditional Doomsday machine.

Traditional two-turn Doomsday machines are difficult to make. In particular, you must be able to sacrifice two large yellows ships. There are only three large yellow pieces in the game, and if two of them are controlled by the enemy (either as ships or stars), a traditional Doomsday machine may be impossible.

However, there are Doomsday machines with lower material requirements. They simply require extra turns to operate. Doomsday machines usually destroy the two stars in two separate phases: bring in ships to destroy one star, then bring in ships to destroy the second star. (It's an interesting challenge to find a position where the phases must overlap in order to succeed, in other words, where a ship of the second stars color must be sent to the enemy home before the first star is destroyed.)

Each phase can take 1-3 turns to complete. If each phase can be completed in one turn, then it's a traditional Doomsday machine.

If your opponent didn't notice your Doomsday machine as it was being constructed, they will probably see it once you move ship(s) to their home. They will look for ways to interrupt your machine's execution. Make sure that there's nothing they can do between your turns that will interfere.

I'll emphasize that, in a three-turn Doomsday phase, the second move needs to be a double threat: if your opponent attacks your large ship, you can move in the last ship for the catastrophe (just like you planned). But if they instead use that turn to reduce the concentration of that color (by sacrificing, moving, or trading the captured invader), then you need to be prepared to switch your game plan to winning by direct assault. This direct assault has a one-turn head start since your opponent spent a turn responding to the catastrophe threat. You need to carefully compare your red power with that of your enemy to determine who wins the fight if you begin trying to capture all of their home ships.

In the image below, Beta has assembled a Doomsday machine with two three-turn phases. In the notation I use in the glossary, this is a 3g/3y Doomsday machine. Notice that it would not work as a 3y/3g machine (overpopulating yellow first then green) since the yellow ships are needed for the greens to advance.

Beta safely destroys both homestars of Alpha via

Alpha
Beta
1...
move g1 Betelgeuse Alpha
2.
attack g1 Alpha
2...
move g3 Altair Alpha
3.
attack g3 Alpha
3...
move g1 Altair Alpha
catastrophe Alpha g
4.
trade b3 g3 Alpha
4...
move y1 Altair Alpha
5.
attack y1 Alpha
5...
move y3 Betelgeuse Alpha
6.
attack y3 Alpha
6...
move y1 Altair Alpha
catastrophe Alpha y

In the particular scenario above, Alpha must attack on moves 2 and 5 because otherwise Beta may achieve the catastrophes by sacrificing g3. In many scenarios, the defender may simply ignore the small invading ships and use the turn productively. Sometimes, they may use that turn to launch a counterattack, either on the Doomsday machine or on the attacker's homeworld. Before you engage your slow Doomsday machine, make sure your opponent can't use the spare time to ruin your plan.

Importantly, the three-turn Doomsday phases does not usually work on red stars (see here).

No slow red catastrophe

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Your opponent can't usually cause a red catastrophe against you by moving red ships one at a time. If they attempt this, here's what should happen

  1. They move a red ship into your system.
  2. You attack the first red ship.
  3. They move another red ship into your system.
  4. You sacrifice the first red ship to attack the second red ship.
  5. They see the error of their ways.

For example, in the position below, Beta has just blundered by moving r3 into Alpha's home. Alpha should sacrifice the r1 and attack the invader. Beta has regrets.

You should check your own situation carefully, however. You must have a ship large enough to attack any invading reds, and—if you are defending a red system marker— you shouldn't let your only large ship be a red one. If your only large ship is red as well as a system marker, then you won't be able to sacrifice the r3 to attack an invading r3, so a slow red catastrophe can happen when your opponent moves in with their second red ship.

Textbook direct assault

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Of the three paths to victory, the direct assault seems to get the least attention. Every strategy guide talks about Doomsday machines (the surest way to achieve star demolition) and the Bluebird mistake (allowing a game-losing fleet catastrophe). New players may not have a clear idea of how a direct assault occurs, so their first exposure is likely to be a defeat they didn't see coming.

Typically, every player has a large ship in their homeworld and a red ship someplace (which they could sacrifice). If your opponent doesn't have a red ship, they'll probably at least have a planetary defense system. So if you move any ship into your opponent's home, they'll just capture it, right?

Not if you invade with several ships at once so that they can't all be captured. Your opponent's defenses will determine the size of the invasion fleet you need. Say that

If R+L is more than 3, then a basic direct assault won't work. You could theoretically have a two-wave invasion with more than three ships, but that's more complicated than I'm going to illustrate here.

Here's what you need:

Here's the battle plan:

  1. You sacrifice your yellow ship and move your R+1 large ships into your opponent's home
  2. They sacrifice their largest red to attack R of your invading larges (you still have one left)
  3. You sacrifice your red ship to attack the R ships that they just captured as well as the L large ships that they had to begin with.

You now have two or more large ships in your opponent's home and they have none. Usually, their only defense at this point (besides a counterattack) is to catastrophe your larges.

Compared to catastrophe-based wins, direct assaults can be difficult to plan. When you're invading and capturing ships, you need your ships to stay alive (unlike when you're pushing ships into catastrophes). Your opponent has time to fight back, so it can get confusing. You need to examine your own case carefully to figure out how to invade.

Examples

Below are some positions where the player "Beta" is considering a direct assault on the enemy homeworld. Below each figure is some analysis including a table of the expected commands if Beta attempts an invasion.

Beta wins with a basic direct assault.

Alpha
Beta
1...
sacrifice y2
move y3 X Alpha
move g3 X Alpha
2.
attack y3 Alpha
2...
sacrifice r2 Beta
attack y3 Alpha
attack g3 Alpha

Beta wins with a basic direct assault.

Alpha
Beta
1...
sacrifice y3 Beta
move y3 X Alpha
move g3 X Alpha
move b3 X Alpha
2.
sacrifice r2 Y
attack y3 Alpha
attack b3 Alpha
2...
sacrifice r3 Beta
attack y3 Alpha
attack b3 Alpha
attack r3 Alpha
3.
build g1 Alpha
3...
sacrifice r3 Alpha
attack g1 Alpha
attack g1 Alpha
pass

Beta wins with a basic direct assault.

Alpha
Beta
1...
sacrifice y3 Beta
move y3 X Alpha
move g3 X Alpha
move b3 X Alpha
2.
sacrifice r1 Y
attack y3 Alpha
2...
sacrifice r3 Beta
attack y3 Alpha
attack g3 Alpha
attack g3 Alpha

A basic direct assault cannot work because

So if Beta invades with three, the invaders are simply captured.

Player 1
Player 2
1...
sacrifice y3 Beta
move y3 X Alpha
move g3 X Alpha
move b3 X Alpha
2.
sacrifice r3 Alpha
attack y3 Alpha
attack g3 Alpha
attack b3 Alpha

However, if Beta moves just two ships to Alpha's home, Alpha is forced to sacrifice their only red ship, which reduces Alpha's red power to R=0. Yellow can then launch a second stage with R+1=1 large ship and win.

Alpha
Beta
1...
sacrifice y3 Beta
move b3 X Alpha
move g3 X Alpha
pass
2.
sacrifice r3 Alpha
attack b3 Alpha
attack g3 Alpha
pass
2...
move y3 X Alpha
3.
trade b3 r3 Alpha
3...
sacrifice r3 Beta
attack r3 Alpha
attack g3 Alpha
attack g3 Alpha

Beta has enough material for a basic direct assault, but the invasion still fails because the invading ships are both blue and Alpha can defend with a catastrophe.

Alpha
Beta
1...
sacrifice y2 Beta
move b3 X Alpha
move b3 X Alpha
2.
build b1 Alpha
catastrophe Alpha b

If Beta instead starts by trading one of their B3 ships for another color, a basic direct assault will work.


A basic direct assault would fail because

However, Beta can still conduct a successful invasion by attacking Alpha's only red ship (instead of following the basic direct assault formula by attacking a large ship).

Alpha
Beta
1...
sacrifice y2 Beta
move g3 X Alpha
move b3 X Alpha
2.
attack g3 Alpha
2...
sacrifice r1 Beta
attack r1 Alpha
3.
trade g3 r3 Alpha
3...
attack r3 Alpha