Features

Everything in the build

Written as it is, not as it will be. If something is half-finished it says so on the roadmap instead of appearing here.

Physics

The part that is not negotiable.

N-body gravity in double precision: Every body pulls on every vehicle. Spheres of influence fall out of the maths rather than being drawn on top of it, and the integrator is symplectic and substepped so a long coast does not drift.
Real masses, real distances: The solar system is at 1:1 scale with real masses. Reaching orbit costs about 9.3 km/s of delta-v because that is what it costs.
Atmospheric flight: Per-part drag with stack occlusion, so a fairing genuinely shields what is behind it. Aerodynamic torque, control surfaces that only bite where there is air, and entry heating with an ablator that wears away.
6DOF attitude control: Thrust vectoring, reaction wheels, RCS and aerodynamic surfaces, allocated in that order by an authority model that knows which of them can actually do the job.
Time warp to 10,000,000×: With the guards that matter: warp stops when a burn comes up or the vehicle drifts off course, and thrust is never applied under warp.

Where most of the time goes.

Snap-together assembly: Stack parts, mirror them radially, and place them precisely with a stepper pad and an axis gizmo that also works on a touchscreen.
Parts that adapt: Tanks and fairings taper, and their mass and capacity scale with the volume you actually gave them.
Staging and action groups: Automatic staging you can override, per-part action keys, and multi-selection editing for fuel load, gear state, separation force and thrust limit.
Live numbers: Delta-v and thrust-to-weight per stage, updated as you build, so the rocket tells you it cannot make orbit before you find out the hard way.
Paint and wear: Colors, patterns, 3D finishes and hull text per part — and dust, soot and entry scorch that accumulate directionally and persist across a career.
Undo, redo, subassemblies: Snapshot undo across the whole design, and a saved subassembly you can drop into the next rocket.

Getting somewhere and getting back.

Destination-first mission planner: Pick where you want to go. It finds the window, prices every burn, routes through intermediate bodies when it has to, and plans mid-course corrections.
Burn guidance: Coloured cues and audio for burn-now and cut, a gentle-throttle coach for very small burns, and a plan that replans when you drift.
Click-to-land site targeting: Click a spot on the globe in map view and it works out the deorbit — tilting the plane rather than refusing, because cross-track is the real obstacle, not longitude.
Docking: Four port sizes, magnetic soft capture, and a hard dock that merges two vehicles into one rather than pinning them together with a joint.
EVA and rovers: Put a crew member outside and walk. Or drive: wheels, solar panels and batteries feed a vehicle-wide charge pool through a real tire model.
Block-code automation: Around 160 blocks that snap into a program the vehicle runs. A worked example that flies to orbit ships with the game. Distinct from the ship's own autopilots — the mission planner and the landing guidance above: those fly a plan the game worked out, while an automation you wrote will drop hardware, because you told it to.
Rewind: Fifteen seconds of flight held in memory, so a mistake costs fifteen seconds.

Places worth the trip.

Real surfaces: Imagery and elevation baked from NASA, USGS and ESA data for every body. Land in a named crater and it is that crater.
Weather and sea: Volumetric clouds with per-column tops you can fly through, and an ocean with depth color, sea state, foam, an attenuated seabed and per-part flooding.
A space center: A real campus with a VAB and split apron zones, not a photograph behind the pad.
Career mode: Funds, research, contracts and crew across three sites — or sandbox, with all of it turned off.
Mission log: A persistent per-world record of what you did and when, with the milestones that matter marked.

Things you only notice when they are missing.

Runs on a laptop: Graphics presets from a fanless MacBook Air to a desktop GPU, auto-detected on first launch and every option individually priced.
Phone and tablet: An iOS build with touch controls designed for it, 44-point targets and a HUD that survives a 375-point-tall landscape window.
Screen reader mode: A status readout, keyboard navigation through the map, and a modal layer that genuinely blocks what is behind it.
Interactive tutorials: A catalog of tutorials that run as throwaway sessions, so nothing you learn on costs you a save.
Your files are yours: Craft, worlds, automation programs and settings are plain files in a per-user data directory. Nothing is locked to an account.

Ready to try it?