Engine Notes: five emails on how a rocket engine works

Engine Notes is five emails over eleven days. Each one takes one piece of the engine, or one limit of the model, and shows you the numbers behind it.

By the end you will have the mechanism, the paper the model is written up in, and a list of the things Meco does not do yet. Enough to judge it without buying it.

Complicated and in-depth, this game is closer to a simulation software than a video game, and tackles the complex principles and math behind propulsion engineering.

Rigel the Protogen, recommended on Steam, 15 April 2026

What arrives, in order

1. What this actually is. A rocket engine design sim, and the honest version of what it does. In most space games the engine is a part you pick off a list. Here you build it, component by component, until the whole cycle converges.
2. Four numbers draw the bell. Throat radius, expansion ratio, bell length fraction, throat arc factor. Then what happens in the flow field when you push the expansion ratio past what sea level will hold.
3. Go and argue with the paper. The model underneath is written up as a preprint, DOI and all. You can check my working without buying anything.
4. What Meco does not do yet. Ignition, tanks, wall temperature limits, combustion instability. Four of the Early Access gaps, from me rather than from a review.
5. Build a Merlin 1D. The mission that opens Chapter V, and a debrief that walks back through the startup you authored and the propellant flows and chamber pressure you tuned it to. The internals have never been published, so every figure in there is derived rather than a blueprint.

That is the whole series. After it you get the ordinary build log: what changed in the simulator, what broke, and what the numbers said, plus what is going on in rocket propulsion outside Meco. The engine that just ran on a test stand, the cycle somebody revived. Building this thing means reading that literature anyway, so I pass the notes on. Usually one or two a month.

Steam gets the release note. This gets the reasoning behind it.

If you would rather read one before you hand over an address, the most recent is Meco 0.6: Engine Assemblies.

What you can check

I build Meco on my own, and the engine model behind it is published: DOI 10.5281/zenodo.21864769. It is a preprint, and it is careful about what it claims. It grades two mass residuals on a frozen case, a Merlin 1D class engine assembled from public data, and reports both of them. That is verification, not validation against a real engine's flight record. Read it and decide for yourself.

Two other places to follow Meco

The store page carries the reviews, the screenshots and the discussion boards. It is where you buy Meco, and where the release notes land.

Discord is the quickest way to reach me. Ask a question about an engine you are building, or watch other people argue about nozzle contours.