Build a rocket, fly it to orbit, and chase the contracts. Real orbital mechanics, real Tsiolkovsky physics, two moons to visit.
Builder
Click parts on the left to stack them. S0/S1/... buttons assign stages. Stage with the highest number fires first. Use the MunShip preset if you want a ready-to-fly design.
Flight — the 10 keys you need
W/S throttle A/D pitch Q/E yaw Space stage
0-9 SAS modes (prograde, retrograde, target, etc.)
L autopilot (ascent on Earth — moon landing once in Mun/Minmus SOI)
M map view N maneuver node ,/. time warp
G deploy chute Shift+WASDQE = RCS translate (precision docking)
First mission
Load MunShip, press LAUNCH, then hit L to let the autopilot put you in orbit. On the maneuver panel click → Mun, warp (.) until the burn window, hit 8 for SAS MANEUVER, then W to throttle up.
SAS
★ MANEUVER NODE
+0s
0
0
0
MAP LEGEND Orbit Periapsis Apoapsis Ship
Drag: rotate Wheel: zoom
W/S Throttle A/D Pitch Q/E Yaw Shift+move=RCS SPACE Stage 0-9 SAS M Map N Node G Chute X Abort L Autopilot ,/. Warp Drag/Scroll=Camera ESC Quit
Orbit Achieved!
About Apoapsis
Apoapsis is a 3D rocket-flight simulation. Plan an ascent profile, manage staging, and reach a stable orbit around Earth — or beyond. Real Newtonian gravity (no patched conics simplification), realistic engine specifications, and atmospheric drag matter to your trajectory.
How to play
Configure your rocket: payload, stages, fuel mass. Throttle up, gravity-turn during ascent, stage at appropriate altitudes, circularize at apoapsis to lock in orbit. Three.js renders the trajectory in 3D; orbit parameters update live.
Frequently asked questions
What is apoapsis?
The highest point of an orbit — opposite of periapsis (lowest point). On Earth it's "apogee"; for the Sun it's "aphelion". The game is named after this orbital concept.
Is the physics realistic?
Yes — full Newtonian gravity (no patched-conics simplification), realistic engine ISP/thrust specs, and atmospheric drag with altitude-dependent density. Trajectory matches what Kerbal Space Program calls "Realism Overhaul" closely.
What's a good gravity-turn altitude?
Begin pitching over at ~5 km, target ~45° pitch by 20 km. Earlier pitch wastes fuel on horizontal velocity at sea level (high drag); later pitch wastes fuel fighting gravity.
Can I land on the Moon?
Single-stage to orbit and a circumlunar flyby are both achievable with the default rocket. A surface-landing mission requires a custom multi-stage build.