Coinko

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.

Rebuild a portrait/mobile-friendly arcade idle Plinko game titled “Coinko.” Use a dark navy casino/arcade presentation with a tall, front-facing 3D board viewed through an orthographic camera. The scene background is deep navy (#07101d) with a slightly lighter blue rectangular board interior, subtle fog/glow on capable devices, and thick blue side rails, top cap, bottom floor, and bucket dividers. Keep the board centered and nearly full height; it is approximately 20 world units wide and runs from y=12.8 at the top to the payout area near y=-11.15. Render the board as simple flat geometric meshes with soft lighting where available, not realistic textures.

Gameplay: the player drops free yellow Plinko balls from the top of the board. Balls fall under gravity, bounce off a staggered grid of 10 rows of pale blue circular pegs, bounce from the side walls, and eventually resolve into one of 9 payout buckets at the bottom. Use lightweight custom collision physics: balls have radius about 0.29, pegs about 0.38, gravity around -22.5, bouncy peg and wall collisions, and a little horizontal jitter on peg impacts. The payout multipliers from left to right are exactly: 1x, 1.5x, 2x, 3x, 6x, 3x, 2x, 1.5x, 1x, with the center 6x slot visually highlighted in gold/brown. When a ball reaches the payout lip, calculate its bucket from its x-position and award money equal to the slot multiplier times all applicable multipliers. Show small gold spark particles on normal-device payouts. Balls should visibly be pale yellow; unlocked Golden Balls can spawn as brighter glowing gold balls and cash out for a much larger bonus.

Start the run with $0, no upgrades, no rebirths, no balls live, and a permanent rebirth multiplier of x1. Every normal Drop Ball action creates one ball by default; a Burst Drop upgrade adds +1 ball to every burst. The large “Drop Ball” button performs one burst, while “Drop Burst” performs 4 bursts at once. Clicking/tapping anywhere on the board drops a burst at the horizontal location touched. Holding on the board continuously pours bursts at the held horizontal position, and dragging while holding changes that position. The “∞ Rain” button toggles endless free spawning across random horizontal positions; show whether it is On or Off. An Auto Dropper upgrade automatically fires bursts at a rate of 0.8 bursts per second per level. Rain Engine increases the rain/held-drop rate; base rain is 4 bursts per second on normal devices (2.5 on performance/mobile mode), plus 3.5 per Rain Engine level (2.2 on performance/mobile mode). Cap active balls around 420 on desktop and 220 on performance/mobile mode, resolving/removing the oldest if necessary.

Money progression: display current money, total multiplier, auto-drop rate, live ball count, and rain status in a top-left translucent rounded HUD panel. The HUD should look like the reference: small uppercase “COINKO,” a large yellow dollar amount, and a rounded “Rebirth x1” chip at the top right of the panel. Under the money, show labels such as “Total x1.00,” “Auto 0.0/s,” “0 balls live,” and “∞ Rain Off.” Use a responsive portrait layout and make the controls large, high-contrast, rounded buttons docked in the lower portion: yellow “Drop Ball,” blue “Drop Burst,” brown/gold “∞ Rain,” and blue “Open Shop.” Include a slim instruction pill above the buttons reading: “Tap board or use the docked buttons below. Open Shop has upgrades and rebirth.” At the very bottom, show a horizontal payout bar with nine dark rounded cells labeled with the multipliers, with the central 6x cell highlighted.

Implement the upgrade shop as a dedicated overlay drawer/modal opened by “Open Shop,” rather than permanently filling the screen. It should be closable via a close button, backdrop click, or Escape, and should show current money, total earned, current rebirth multiplier, rebirth count, and a rebirth section. Display eight upgrade cards with level, description, current effect, escalating cost, and Buy button:
1. Money Multiplier: cost floor(10 * 1.7^level), increases all payouts by +35% per level; total money multiplier is 1 + 0.35 per level.
2. Burst Drop: cost floor(25 * 1.9^level), adds one free ball to every burst.
3. Auto Dropper: cost floor(40 * 2.15^level), adds 0.8 automatic bursts per second per level.
4. Golden Balls: cost floor(120 * 2^level), gives up to a 50% chance (6% per level) for a gold ball; golden payout multiplier is 4 + 0.5 per level.
5. Jackpot Boost: cost floor(220 * 2.22^level), multiplies the center bucket by 1 + 1.2 per level and the adjacent buckets by 1 + 0.35 per level.
6. Center Magnet: cost floor(320 * 2.35^level), gently pulls balls toward x=0 with strength 0.18 per level.
7. Crit Cash: cost floor(600 * 2.5^level), gives up to a 60% payout critical chance (5% per level), with critical multiplier 2 + 0.25 per level.
8. Rain Engine: cost floor(900 * 2.65^level), increases infinite rain and held-drop speed.

A payout should be: base slot multiplier, multiplied by Jackpot Boost for center/near-center buckets if applicable, multiplied by the Golden Balls bonus if golden, potentially multiplied by Crit Cash, then multiplied by the ordinary Money Multiplier and permanent Rebirth multiplier. Format money compactly for large totals. Disable Buy buttons when unaffordable.

Rebirth is available in the shop at a cost of floor(50,000 * 4.2^currentRebirths). The initial cost is therefore $50,000. When affordable, the Rebirth button resets current money to zero, resets all eight upgrade levels to zero, clears active balls and payout particles, stops rain, and increments rebirths. Each rebirth permanently doubles the rebirth multiplier: x1, x2, x4, etc. Show the next rebirth multiplier and a status message explaining whether more money is needed or the reset is ready.

Support keyboard controls matching the original: Space or D drops a burst, B drops 4 bursts, I toggles infinite rain, O opens/closes the shop, R attempts rebirth, number keys 1–8 buy the corresponding upgrade, and Escape closes the shop. Ensure touch buttons remain clickable over the canvas on mobile, prevent accidental page scrolling while interacting, and adapt the orthographic camera and renderer on resize. Use simple responsive HTML/CSS HUD overlays over a Three.js/WebGL canvas; keep the art clean, minimal, glossy, and high contrast with pale blue pegs, golden balls, navy panels, and blue structural rails.