This is a submission for the June Solstice Game Jam

What I Built

SOLSTICE — The Longest Day is a short, atmospheric platformer built around one idea: your light is your only resource.

It's the eve of the June solstice — the year's hinge between the longest day and the longest night — and the sun is failing. You play a small wanderer carrying the last ember of daylight. That glow does three jobs at once:

• It lets you see. The world is dark; you move inside a soft pool of light that shrinks as it drains.
• It's your lifeline. Shadow drains it faster — let it gutter out and you're nearly blind.
• It's your tool. Spend it in a Sunburst to bloom pale, ghostly platforms into something solid, light distant beacons, and push back the dark.

You carry that light across four hand-built levels — Dusk → Twilight → Deep Night → The Turning — as the darkness deepens, until you reach the altar and rekindle the dawn.

My goal & the theme: the solstice is the exact instant light and dark trade places, so I wanted light to be something you physically negotiate the whole game rather than just a backdrop. Spend too much and you're stranded in the dark; hoard it and the path stays shut. The level arc traces the day itself — a descent into the longest night, a turning point, and a climb into a dawn that floods the screen with gold.

▶ Play it in your browser (desktop & mobile): https://hyperagent.com/s/A_Xul17aTbCIAsAcvG8A-w

Code

The entire game is a single, self-contained index.html — HTML5 Canvas 2D + vanilla JavaScript, no engine, no libraries, no build step. One file you can read top to bottom.

How I Built It

Lighting is the heart of it. Each frame I draw the world normally, then build a separate darkness layer: fill it near-black, then punch holes in it with radial gradients at every light source (you, motes, beacons, lit platforms) using globalCompositeOperation = 'destination-out'. Composited over the scene, that gives the soft pool-of-light look; a second additive pass paints warm bloom back in. Platforms that are only solid when lit simply test, each frame, whether their center falls inside a light radius — that one check is the whole core mechanic.

Game feel got real attention: a fixed-timestep loop, coyote time, jump buffering, variable jump height, squash-and-stretch on the character, a little screen shake on landings and Sunbursts, and an eased camera. Small touches, but they're the difference between a canvas platformer feeling crisp vs. stiff.

Audio is fully synthesized with the Web Audio API — no sound files. A warm, consonant sine pad drones under everything, with gentle chimes for motes and a soft whoosh for the Sunburst.

It's responsive & mobile-first: the canvas adapts its aspect ratio to fill any screen, and the touch controls are true multi-touch so you can move and jump at the same moment (with touch-action: none so the browser doesn't hijack the second finger as a zoom).

A few things I wrestled with: keeping a draining-resource game fair (generous minimum light, forgiving beacon checkpoints); a collision bug where a rising platform briefly overlapped the player's feet and flung them sideways; and tuning the dawn so it reads as a warm sunrise payoff instead of a blinding flash.

Thanks for playing, and happy solstice. ☀️