Railborn

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 playable low-poly 3D third-person sandbox game titled “RAILBORN // VR SANDBOX SLICE.” Use Three.js-style rendering with a perspective camera following the player from behind at roughly a 7-unit distance, with click-and-drag/right-look style camera control and a small circular crosshair centered on screen. The scene is a simple outdoor railway station under a dark blue-gray sky with fog: a large muted olive-green ground plane, a broad light gray station platform around z=9, a dark blue-gray flat roof above it, and a yellow/orange vertical platform sign. Use soft stylized lighting with a cool hemisphere fill and warm directional sunlight, shadows, and simple Kenney-like low-poly assets.

The player is a small animated monkey avatar, initially on the platform near (0, 0, 8). Place a red diesel locomotive/train at approximately (0, 0, -4), consisting of a locomotive followed by two box cargo wagons. Lay out three parallel railway lines at x=-5, 0, and 5, extending from about z=-28 to z=28. Add animated monkey NPCs at approximately (-3,-9), (3,-15), and (8,-22). Add five collectible banana props at (-3,7), (3,12), (-3,18), (3,24), and (8,2), slightly above the ground.

The main loop has two modes. In station/on-foot mode, move the monkey with WASD or arrow keys, jump with Space, and collect a banana when within about 1.5 units; remove it and increase the score by 1, showing a bottom-center toast such as “Banana eaten +1.” The player can throw/use a grenade shockwave with G: while not driving, every nearby NPC within 8 units is knocked upward (raise its vertical position by about 3 units), marked stunned, and the score increases by 1 per affected NPC; show “Grenade shockwave — physics knockback triggered.”

When the player is within 4 units of the locomotive, pressing E boards it and switches to train mode. In train mode, attach/follow the monkey to the train and show that the player has become the train. Use W or Up Arrow to throttle forward and S or Down Arrow to reverse/brake: smoothly damp the train speed toward +10 or -10, and move the train along the z axis according to its speed. Use A/Left Arrow and D/Right Arrow to smoothly move the train laterally toward the x=-5 or x=5 tracks. While moving faster than 3 units, if the train comes within about 2.2 units of an unstunned NPC, knock that NPC upward by about 2.5 units, mark it stunned, add 1 to the score, and show “Impact! NPC ragdoll knockback.” Press E again in train mode to disembark, leave the player just to the side of the train, and show “Back on the platform.” Do not let banana collection run while in train mode.

Include a fixed translucent dark HUD panel in the upper-left with rounded corners. It must display the gold title “RAILBORN // VR SANDBOX SLICE,” a status line that changes between “STATION • bananas [remaining] • score [score] / Find the red locomotive and press E” and “TRAIN MODE • speed [one decimal] • wagons smashed [score] / Press E to disembark,” four clickable rounded color swatches (red, blue, green, purple), and the instruction text “WASD / arrows move • Space jump • E board train • W/S throttle • G grenade • click to look.” Start with the red swatch selected. Clicking a swatch changes the train and monkey body/material color to the selected red (#e85d5d), blue (#4e9cff), green (#55c878), or purple (#c17cff), and display “Train + monkey color updated.” Add a rounded bottom-center toast notification that fades away after a short delay. Keep the aesthetic sparse and prototype-like: simple geometric station structures, visible tracks, low-poly animated monkeys, train and bananas, no extra enemies, weapons, menus, or invented objectives.