Press Kit

The Meco Rocket Simulator wordmark.

Meco Rocket Simulator is a rocket engine design simulator. You set the geometry of a real engine, fire it, and read what comes back on live graphs. Every node is inspectable, and nothing important happens in a box you cannot open.

It has been on Steam Early Access since 14 July 2025. The current release is 0.6.1. It is built by one person, Dannie Sim, at Loren Aerospace Ltd in London.

Quick facts

Title: Meco Rocket Simulator
Developer and publisher: Loren Aerospace Ltd, London, United Kingdom
Team size: one
Platforms: Windows and macOS. Linux coming soon
Release: Steam Early Access, 14 July 2025
Review keys: available on request, email admin@mecorocketsimulator.com
Current version: 0.6.1, 30 August 2026
Genre: rocket engine design simulator, single player, no combat
Optional add-on: Pro DLC, with the soundtrack, technical reference PDFs, 3D-printable component models and wallpapers. It contains no gameplay.
Price: shown live in the Steam block below, read from Steam at build time. Early Access pricing steps up as the roadmap fills in, so quote the figure on the store page rather than this page if you are writing ahead of publication.
Contact: admin@mecorocketsimulator.com

Three things that make it worth a look

The thrust number comes from the flow field, not a lookup table

Meco integrates the method-of-characteristics flow field through the bell you designed, at the mass flow the simulation actually delivered. Push the expansion ratio too far at sea level and the flow lets go of the wall. The field view grays out from the separation point onward, and thrust is counted only where the flow is still pushing.

The Nozzle Field view of an over-expanded bell. The flow is colored by Mach number near the throat and turns flat gray from the separation point onward. The card beside it reads 709.3 kN of thrust, Isp 243.0 s, and Flow Separation: Yes.

The hardware builds itself from a handful of numbers

Give the Thrust Chamber a throat radius, an expansion ratio, a contraction ratio, a chamber length and a section count. It returns a Rao thrust-optimized bell, the regenerative cooling channel layout and the chamber solids in 3D. Change one headline number and the hardware rebuilds while you watch. The Turbopump does the same for shafts, gears, pumps and turbines across four shaft layouts.

$The Thrust Chamber editor. A nozzle contour is drawn in section with its four numbered stations, and the panel beside it holds a throat radius of 12.9 cm, an expansion ratio of 16 and a bell length fraction of 0.8, with the copper bell rendered in 3D underneath.$

The Turbopump assembly in 3D with casings and housings hidden. Two impellers sit on their shafts above a large gear train, the configuration reads direct drive plus geared pump, and the slot list names every shaft, gear, pump and turbine stage.

The engine model is published, with a DOI

The coupled gas-generator engine model behind the simulation is written up in a public paper, demonstrated on the Merlin 1D, so a reader can check the work rather than take it on trust: 10.5281/zenodo.21864769.

Two more numbers for the record. The solver advances the state of the engine 50,000 times for every second of engine time, at a fixed step. And the built-in Vulcain 1 model sits on its published performance figures: an automated test holds its engine Isp within 1% of the published 431 seconds.

How you play it

Assemblies are parts of an engine, not the engine. On the node graph canvas you drop in components, wire them together and run. Domes, injectors, valves, cooling joints, gas generator, turbine. It is your plumbing, and it fails in your handwriting.

The Merlin 1D flow network on the node graph canvas: LOX and RP-1 domes feeding injectors, the main combustion chamber column with its throat and nozzle cooling joints, and the turbopump's pumps, gears and shafts wired through to the turbine and exhaust.

The start is a schedule too. One master ramp runs 0 to 1, and each valve fires as it crosses its own threshold, with its own level, width and delay. Real engines go in order: spin up, crack the valves, light the gas generator, trim.

The Merlin 1D startup schedule. The LOX and RP-1 ramp components sit on the flow network above a live controls chart of valve positions against time, and the component editor beside it holds the target valve opening, driver scalar, offset and delay with a signal preview.

There are fourteen missions across five chapters. Mission 0 drops the player at senior engineer Miku Aoyama's workstation with her Vulcain 1 model open and a clear instruction not to touch it. Chapter V opens with the engine that flies Falcon 9.

Your first designs probably will not hit their targets. That is the point. In a mission, when a build misses, a "Need a hint?" diagnostic names the specific problem and walks you to the fix one item at a time. In free build there is no tutor. There it is you, the graphs and the hardware rebuilding as you type.

Mission 0 in progress. Miku Aoyama's brief sits in the right panel above an objective list, the Need a hint? button is highlighted below it, and the Vulcain flow network with its live charts fills the rest of the screen.

What shipped in 0.6

0.6 arrived on 26 August 2026, and the 0.6.1 patch on 30 August.

Engine assemblies. The Thrust Chamber builds a Rao thrust-optimized bell and tiles its regenerative cooling channels from a handful of inputs, live in 3D. The Turbopump sizes its own shafts and gears across four shaft layouts.
Mission 13, Historical Recreation: SpaceX Merlin 1D. The first mission of Chapter V, and the capstone of the fourteen. The debrief puts your numbers next to the published Merlin figures. Afterwards the Merlin 1D is a free-build template, yours to keep tinkering with.
Chained startup control. One master ramp drives every valve on its own threshold, level, width and delay.
Undo and redo, across the editor.

Playable now: Chapters I to IV complete, Chapter V open with the Merlin 1D. Thrust Chamber and Turbopump assemblies in live 3D. Engine Isp, the number real datasheets quote, with the gas generator's propellant counted against it.

Building next: the rest of Chapter V, the A-7 Redstone and the Vulcain 1. The Injector Head assembly in coaxial, pintle and impinging configurations. Expander-cycle components. The whole engine joined into one machine in 3D. Component mass, for thrust-to-weight numbers. Thermal and load stress limits. The roadmap is intended to finish in 2027.

A converged Merlin 1D run. Feedline, turbopump, combustion chamber and gas generator charts all hold steady, the nozzle field is colored by pressure, and the thrust card reads 849.6 kN with a nozzle-flow Isp of 291.2 s.

Who it is for

Propulsion-obsessed tinkerers, amateur rocketeers, university rocket clubs, and aerospace and mechanical engineering students. It is not a casual space game. It is an engineering sim with a real learning curve, and it is at its best when you want to know why a cycle works.

What players are saying

Verbatim from Steam reviews.

If you have an interest in the design and function of rocket engines this is the game for you! 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

I love this game! it is the first software i could find that gives you access to this kind of rocket simulation thats not blocked to the greater public. although it is a steep learning curve, there is a great community around it and plenty of people willing to help.

iset07wick

As a mechanical engineering student, I enjoy learning a lot about rocket science from this game as it reminds me of the concepts ive learned in my propulsion and turbomachinery classes where thermodynamics, fluid mechanics, heat transfer and some concepts of mechanical design are implemented into rocket design.

CGlassMan

This game, or i would like to call it more a "Tool" is great for someone who like's to understand more physics (fluids/ dynamics/ etc..) and micro physics related to engines.

HTK

Press assets

Video and streaming. You can record, stream and monetize video of Meco Rocket Simulator anywhere you like. No permission needed, no revenue share, and nothing to sign.

The assets below are free to use in coverage, in print, online and in video, with credit to Loren Aerospace Ltd. Screenshots and trailer footage can be cut, cropped, captioned and edited into your piece, music included. Logos and artwork are crop and scale only: no recolouring, no redrawing.

Trailer

Screenshots, 1920 x 1080 PNG

Logos

The Meco Rocket Simulator square logo in gray.

For anything not listed here, including higher-resolution art or raw footage, email admin@mecorocketsimulator.com.

About Loren Aerospace

The Loren Aerospace logo.

Loren Aerospace Ltd is a company registered in England and Wales, number 14563299, at 71 to 75 Shelton Street, Covent Garden, London, WC2H 9JQ. It was founded by Dannie Sim, who spent 25 years in technology startups, in scientific publishing, and in games at Activision Blizzard on Candy Crush and at Sony PlayStation on Spider-Man 2. He builds Meco alone.

Loren Aerospace develops Meco Rocket Simulator and LorenSim, the simulation library underneath it, which is published for non-commercial and academic use.

To be a spacefaring civilization we need a lot of people who can build and maintain rocket engines. That is a teaching problem before it is a hardware problem, and Meco is the answer to it that one person can build.

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