Pocket Kerbal

Cinevva's analyzer read this game's design doc and its source, then wrote the brief below. "Make your own" hands it to the game creator as your opening message, so you start from a real spec rather than a one-line idea.

Create a lightweight 3D Kerbal-like rocket flight sandbox titled “Pocket Kerbal.” Render a dark space scene with a black/deep navy background, a sparse starfield of many small white-blue points, and a small green spherical planet (radius roughly 50 world units) with a translucent blue ocean-like overlay and a faint light-blue spherical atmosphere shell extending above the surface. Put a dark gray circular cylindrical launchpad on the planet’s surface. Use a simple primitive-built rocket standing vertically on the pad: a light gray/white cylindrical central rocket with a pointed nosecone, dark nozzle, and a yellow accent ring, plus a larger lower booster stage that is visibly dropped/hidden when staging. Keep the visual style clean, minimal, low-detail sci-fi with physically lit primitives and a faint dark fog.

Implement a playable simplified orbital-flight model. The rocket is a point mass with world position and velocity, starting just above the planet surface at rest, with its local +Y axis as its thrust direction. Apply central inverse-square gravity using a fixed gravitational parameter, quadratic atmospheric drag below the atmosphere boundary, and a mild atmospheric tendency to align the rocket with its prograde velocity. Integrate movement continuously with stable small substeps. Align the rocket’s visual +Y axis to the radial direction away from the planet, while allowing user steering as a relative rotation. Apply throttle-scaled thrust and consume fuel according to thrust, specific impulse, and gravity constant. Stage 1 has about 7.0 tons of fuel, 1.6 tons dry mass, and 150 thrust with Isp 260; stage 2 has about 3.2 tons fuel, 1.0 ton dry mass, and 85 thrust with Isp 320, with a small payload/main dry mass. When stage 1 is staged, hide/drop the booster and activate the core; when stage 2 is staged, cut the engine. If fuel is depleted, show a prompt-like status telling the player to stage. Handle ground contact: gentle contact settles the rocket and can show “Landed,” while impact with sufficiently negative radial speed marks it crashed, stops it, and asks the player to reset.

Controls: W increases throttle gradually and S decreases it; arrow keys steer with pitch/roll-like torque (up/down and left/right), with angular damping and integrated orientation; Space stages (booster to core, then engine cutoff); R resets position, velocity, fuel, stage, attitude, crash state, throttle, and status; C toggles between an automatic follow camera and a freely orbitable camera. In orbit-camera mode, support mouse drag to orbit and scroll to zoom, without panning. The follow camera trails behind and above the rocket based on its current orientation and smoothly looks toward it. Include a soft synth engine tone whose volume/frequency follows throttle and short synth blips for staging, reset, camera toggle, and crash, initialized after the first click or keypress.

Add a fixed minimal HUD in the upper-left/upper area over the canvas. Show the title “Pocket Kerbal,” a compact help line exactly indicating the controls (“W/S throttle • Arrows steer • Space stage • R reset • C camera”), and an 4-column responsive grid of translucent dark rounded cards with subtle blue borders. The cards must display live values for Throttle (percentage), Fuel (tons, or em dash after all stages), Altitude (km), Speed (km/s), Apoapsis (km), Periapsis (km), Orbit, and Status. Estimate orbital elements from specific orbital energy and angular momentum: classify unbound trajectories as “Escape,” bound trajectories whose periapsis is not above 5 km as “Suborbit,” and bound trajectories with periapsis above 5 km as “Orbit”; show em dashes for unavailable apoapsis/periapsis. The initial state should read 0% throttle, 7.00 t fuel, zero/near-zero altitude and speed, unavailable apsides, and a ready/landed-style status. When a stable orbit is achieved, update status to “Stable orbit achieved — nice!” Provide reset/restart behavior and preserve the uncluttered HUD and black-space presentation shown in the reference.