As I work on the next few steps in the Architect of Worlds design sequence, I’ve realized that I can save myself a lot of hassle by tweaking a couple of the steps I’ve recently posted.

So, for those of you who are following along and experimenting with the sequence as I post it, here are two minor changes you may want to consider implementing immediately. The next few steps are going to assume these modifications are in effect.

Under Step Twenty-One, add the following right after the “Status of Lithosphere” block:

---

Special Case: Molten Lithospheres and Prevalence of Water

If the world has a Molten Lithosphere, and its prevalence of water is not Massive, then it cannot currently support liquid-water oceans or ice sheets. Reduce the prevalence of water to Trace. This does not constitute a runaway greenhouse event. If the world’s surface cools in the future, water may appear.

---

The idea here is to avoid cases where the world’s surface is covered with molten lava and yet somehow has significant liquid (or even solid) water. Of course, if the world has so much water that its surface is going to be covered hundreds of kilometers deep, even a Molten Lithosphere isn’t going to be able to evaporate all of it.

Next modification: under Step Twenty-Three, beginning with the paragraph that starts “Make a list of the atmospheric components that meet both conditions . . .” and ending with the block titled “Third Case,” replace the text with the following:

---

Make a list of the atmospheric components that meet both conditions, and then refer to the following three cases. In each case, the world will also be assigned an atmospheric class of I through V, which will be relevant in later steps of the design sequence.

First Case

This case holds if one or more of molecular hydrogen, helium, or molecular nitrogen meet both conditions from the table.

In this case, roll 3d6 and modify the result as follows:

• +6 if the world has Massive prevalence of water
• +6 if the world has undergone a runaway greenhouse event
• +6 if the world has a Molten Lithosphere
• +4 if the world has a Soft Lithosphere
• +2 if the world has an Early Plate Lithosphere
• -2 if the world has an Ancient Plate Lithosphere
• -4 if the world has a Solid Lithosphere
• -2 if the world has a Moderate Magnetic Field
• -4 if the world has a Weak Magnetic Field
• -6 if the world has no Magnetic Field

If the modified dice roll is 0 or less, then the world will have a Trace atmosphere, with an atmospheric mass of zero. Otherwise, multiply the modified dice roll by:

• 10 if the world has undergone a runaway greenhouse event (the world will have a Class I or Venus-type atmosphere)
• 1 if the world has blackbody temperature less than 125 K and Massive prevalence of water (the world will have a Class II or Titan-type atmosphere)
• 0.1 otherwise (the world will have a Class III or Earth-type atmosphere)

The final result is the world’s atmospheric mass. Feel free to adjust this result by up to half of the multiplier.

Second Case

This case holds if the first case does not, but carbon dioxide meets both conditions from the table.

In this case, the world will automatically have a Trace atmosphere, with an atmospheric mass of zero. This will be a Class IV or Mars-type atmosphere.

Third Case

This case holds if neither the first case nor the second case is in effect (that is, none of the volatiles listed on the table meet both conditions).

In this case, the world will automatically have no significant atmosphere, and an atmospheric mass of zero. This will be a Class V or Luna-type atmosphere.

---

Assigning these “atmospheric classes” at this point will make several of the steps, starting with Twenty-Five, much more concise.

That’s all for now. I may be able to post Step Twenty-Four tomorrow, and we’ll see how smoothly the next few steps after that fall together.