2026-05-21

Meco 0.5: Don't Break the Cycle

"We wrapped the cycle missions while you were out. Try not to set anything important on fire."

Miku

Meco 0.5 is out, and it does two things: it closes Chapter IV, and it rebuilds how you get into the game in the first place.

The mission ladder now covers a whole engine cycle

With this release you can go from an empty canvas to a cryogenically cooled gas generator cycle engine without leaving the missions. Chamber and nozzle, regenerative cooling, turbopumps, gas generator, injector. End to end.

Three missions close the chapter:

• Mission 10: Turbopump Integration. A LOX turbopump on a direct-drive shaft, Vulcain-style. Everything the 0.4 missions taught you about pumps and turbines comes together here.
• Mission 11: Gas Generator Genesis. A complete F-1 gas generator cycle. You set up the GG, route the exhaust to the turbine, and tune until the loop converges. Self-sustaining turbopumps decide their own speed and you find out whether they picked a good one. This one took me weeks to get right.
• Mission 12: Injector Insights. An RL-10 inspired coaxial injector. LOX posts, H2 annuli, chamber pressure. Injector geometry turned out to matter far more than I expected when I started modelling it.

Missions 10 to 12 have cinematic intros, and so do the older ones. In the last few days before release every intro got re-rendered with lip-synced voice-over, so your mission director now actually speaks the briefing.

The front door got rebuilt

The 0.4 data was blunt about this. Median playtime was around 22 minutes and the moment the game clicks did not arrive until minute 30. So the on-ramp got rebuilt to bring that moment forward to minute one.

• A new Mission 0, "Don't Touch That." Your first day at Mecodyne. You walk in on Miku's workstation with a Vulcain model already open. She told you not to press Run Test. You press Run Test. The sim runs. Welcome to the job.
• "Need a hint?" on every mission. The game reads what you have actually built, compares it to what the objective expects, and names the specific thing that is wrong. It catches typos. It catches naming something Lox Pump when the objective wants LOX Pump. It points at the mismatch instead of saying "not yet".
• Highlight beacons. Animated arrows pointing at the thing to click next, now twice the size so you can actually see them.
• A pinned mission sidebar. The mission window used to float and you would lose it behind the editor. It stays put now, and the editor makes room.
• Click to place. Click the component, click where it goes. Drag-to-place is gone.
• Objectives unfold as you finish them, instead of arriving as a wall.

Boot the game and you get a short cinematic instead of a white flash, then a Start page with a clear way in. It opens fullscreen the first time and remembers your window after that.

Everything else

Display units landed. Pick the units you want for charts and results. Thrust in lbf instead of kN, pressure in psi. One of the most requested things on the list. The control parameter editor got a parameter type dropdown, charts resize properly on a laptop, and efficiency reads as 82% rather than η = 0.82, which is what your brain wanted anyway.

Underneath: a new gas model prototype for staged combustion and expander cycles, the 3D renderer running on Metal for macOS, and a real correction to the turbopump physics. Efficiency scaling moved from pump head to shaft torque, which changes missions 8, 9 and 11. The 3D method-of-characteristics nozzle solver got a review and a derivative-slot fix.

If you play it and have a minute, a Steam review goes a long way for a project this size.