Starfling: A one-tap endless orbital slingshot game in a single HTML file

Hey HN, I built STARFLING, a simple hyper-casual space game you can play right in your browser.

You orbit a star with a ball. Tap anywhere to release and sling it through space. Catch the next star to lock in orbit and keep going. Miss and it's game over.

The whole thing is just one HTML file with vanilla JS, Canvas, and Web Audio. No frameworks, no build step. Loads in under 2 seconds on phone or desktop.

There's a combo system if you release quick, a skip bonus for jumping over stars, and it gets harder the longer you last. When you die you get a cool trail art picture of your whole run that you can share.

Audio is all generated on the fly and it has haptics too. Pretty satisfying once you get the timing down.

Play it here: https://playstarfling.com?utm_source=hn&utm_medium=showhn

Would love your thoughts on the feel, difficulty, and whether the trail art is fun or not.

Thanks!

I would make restarting much much faster than it is now. That's the most annoying part and it breaks the satisfying chain completely for me. I miss and then have to watch it slowly fall, or struggle to find the reset button. And even if I hit the reset, I have to go through the menu.

At the very least, put the reset and play again buttons in the same spot, so I can just keep tapping/clicking there.

Super Meat Boy is how all games like this should be.

I am completely confused about the orbital mechanics in this game. They seem completely broken; at any rate they do not work remotely like any other simulation I've played with (e.g. Gravitation or Kerbal Space Program). The bodies other than the first body appear to actively deflect the spacecraft away!

I gave Codex 5.4 Playwright MCP access to the site and a prompt of "Use Playwright CLI Skill to open https://playstarfling.com/ and load the game. Work out how to play it, and devise a strategy to win." After a about half a dozen attempts it had figured the game out. Then I prompted it to "Score as much as you can." It wrote itself an auto-play script that just keeps going.

I stopped it running at 10866. That's currently the high score. I appreciate that this is pointless and proves nothing, but I've been experimenting with automating testing games (I work at a gaming company at the moment) so it felt like an opportunity to try an experiment.

Fun. Not sure if this applies on desktop, but on mobile the quick/fast/blazing/skip text often blocks vision of the ball making it harder than it should be to make combos

This is good fun! I’ve added it to the HN Arcade :) https://hnarcade.com/games/games/starfling

Fun, but dark grey text on a dark background? Bit hard to read a bunch of the text.

It also seems like there's gravity coming from off screen assets (or maybe it's the bottom of the screen?) causing the projectile to curve in unexpected ways, and not be captured as strongly by the gravity of the visible objects as I'd expect.

It's cool but the marketing is deceptive and through me off at first.

You're describing this as "orbital" and "starfling" but there seems to be constant downwards gravity. That's not at all how space works. I was expecting every 'star' to have its own gravity that would suck it in.

Fun, but the way they fly doesn't quite match my intuition. Why would an object curve when I send it out on the tangent? Wouldn't that be a straight line unless it's affected by a different gravity well?

Looks and plays quite nicely. I don't know how well it represents the real slingshot physics, but it's quite fun.

I've made a similar little web game based on Lunar Lander, check it out!

https://landed.theelderscripts.com/

The use of the Web Vibration API Navigator.vibrate() is well done! I haven't seen it used much, but it really adds to the game.

(Apparently iOS still doesn't support it [1]? It's been in Chrome for the past 12 years. Maybe someday.)

1. https://developer.mozilla.org/en-US/docs/Web/API/Vibration_A...

Neat, and nice audio, but I wish it were a little more forgiving. Eg. Combos or surviving several jumps might collect "lives" that recover your last orbit if you screw up.

Might also be fun if you encountered powerups as you explore deeper into the map (eg. gravity attraction, project path, etc), or even got to pick between forks in the route. The trail art reminds me of Out There.

I don't see the "orbital" part. Ship flies in straight lines

Doesn't seem that hard, just a boredom endurance

Fun :)

Small idea for improvement: the "fast" text is often over the same space as the ball, which makes it harder to see where the ball would be going.

I like it! One complaint is that if you are going fast it starts to display a "Quick!" (or something like that) message on top of the middle of the screen. This makes me want to continue going quickly, but the message is blocking me from properly seeing the orbit, so I end up trying to keep the streak going and most often launch and miss cause I can't see. Maybe display it off to the side in empty space?

Reminds me a little of an old game called Slingshot[0], I think it implemented the idea much better as you actually had to slingshot and consider gravity. Someone should turn it into a browser game, would be much more fun than this.

[0] https://sourceforge.net/projects/slingshot-game/

>single html file

Looks at imports

>Google Tag Manager

-_-

Game is fun, sure the mechanics aren't like real transfers but this appears to be a quick reflex challenge, not a lesson in astrophysics. The only gripe I have is all the flashes and distractions if I go to fast. I don't want ANY extra visuals when I'm concentrating on rapid shots.

Seriously fun! A first it felt frustrating but it was interesting that at a certain point (after about 10 minutes) I suddenly got an intuitive feel for the ball’s trajectory and it became addictive at that point.

My only gripe is you render the bonus notification too near the ball and it distracts me and makes it harder to keep a combo going.

Nice job. Consider allowing the use of a key (Z, spacebar, etc) in addition to the mouse.

Related but I played a similar orbital minigame a while back on Itch.io which has a bit of a 2D Mario Galaxy feel to it as well.

https://danceswithpixels.itch.io/orbital-slingshot

I got 54, allegedly better than 99% of players. But I also note that a score of zero is apparently better than 32% of players.

Very fun.

If I miss but land back in the old gravitational field, I'd like a retry

I've been looking for a game from the "flash era" that's incredibly similar to this one! It was "fling-this-wad-of-duct-tape-to-clog-the-black-hole" as a metaphor, but I forget the name. It had similar "orbit" dynamics, but the entire game was setting the initial angle/velocity and then the orbits just 'did their thing' from there. This looks really cool! I'm already up to 11 as my best!

If you like this, you will for sure love the game "12 Orbits"!

Scoring 0, 1, 2, 3, or 4 all say better than 32% of players. Something isn't right.

This is neat, but the tap to release controls are unintuitive for me. I much prefer the variant of this game that uses hold, drag and aim as input. This allows much greater control, is more engaging, and thus feels more rewarding and fun. Plus, there's no waiting period for the ball to circle back to where you want it to be.

Tangentially, this is also why I dislike the modern trend of auto-shooters and idlers. The twin-stick shooter is by far the superior control scheme for this type of game, yet for some reason people enjoy having less control and engagement. I never got the appeal.

Fun game! One thing I'd love to see is difficulty modes. An easy mode with some kind of aim guide (maybe a trajectory preview on tap-and-hold?) could help new players get the feel for it, and a hard mode where you control launch speed or angle would add a nice skill ceiling for people chasing high scores.

Really nice and very fast becoming addicted :D. Feedback from my side:

- on desktop (tested in Brave Browser) the speed is faster than on mobile (is this supposed to be ?)

- on desktop would be nice to have a short cut to instantly start a new game (may be on mobile you could calculate early on if the balls curve would have a collision and show a button to directly restart)

I don't get the gameplay.

Ok on touch gravity of the orbiting takes off. And if I don't land the next I start again and get prompted for my email each time.

It reminds me of certain games on NES which could be played for hours, once you lose your 3rd life you start all the way from the beginning.

Here it's the same. With one life.

When you go fast, the text in the center ruins visibility, hurts gameplay

Good art style, terrible UX

You didn't play the game you created

Its a nice start, but there is a certain irritation in that the popup text is directly over the puck. I felt like I was losing more because I couldn't see the puck under the combo counter than anything in the game.

Cool game! I scored 7581 (120 stars) on STARFLING :P

https://pod.sekor.eu.org/@modinfo/statuses/01KNXT3ZQDTHZBDYF...

Really slow on an iPhone 7. Should that be expected? I wouldn’t have thought so.

This is an excellent and distinctly frustrating game Echo comments on restart being faster; maybe having the % stats in the main ui somewhere. Will be recommending this to some friends.

Fun game. Well done. The controls are nice.

Nice, enjoyable.

I did however expect the stars to attract my ship, that combined with the top down gravity vector made it less intuitive.

It also makes it feel like a game happening in earths atmosphere instead of space, it impacts the possible sense of scale.

Still fun :)

I love this and it’s very clean. Only piece of feedback, put the play again button where the scores are as that is where the thumb sits on the phone to do the tapping. Mind numbingly groovy

Good fun! Spacebar should launch, r should reset, maybe I'm imagining it, but it's a lot slower and thus easier on my phone than my MBP.

This is both pretty cool and pretty frustrating as the physics don't really match reasonable expectations.

The text that pops up in the middle obscures the current position making it hard to immediately launch again. Maybe it should be closer to the bottom of the screen?

I have never been worse at a game than I am at this one

Reminds me of One More Line, an older mobile game with very similar mechanics.

Took a little bit of figuring out why I always exploded. The restart button was right where I tapped to launch.

I loved the simplicity, it was fun!

Hmm, you can't fall back to a previous orbit. Those don't detect your presence

My most planets is 14, but my highest score is 25 with 8 planets.

The game is pretty fun. Page height is a bit wrong on mobile, you probably need some dvh height?

Spacebar should launch. I should be able to use arrow keys to speed it up.

Very fun! If you play it on a big monitor, the games slows down for some reason.

Love it, but bro you got to make the process of staying playing in the first 2 minutes simpler.

Right now the first 5 or so times you miss. Probably the first 5 times you try.

You get an annoying process of having to shift you hand to press the play again button.

The solution is easy as checking what the game score and high score is, if it's 0 just restart.

I don't need or want to hear about how to sign up to your mailing list if I've just fallen flat on my face!

There's a reset button but it seems to do nothing and you end up at the play again screen.

hmm, it isn't strictly gravitational projectile movement isn't it?

I love it.

But why make apps for it? The web page is perfect as is

Lack of proper physics really bothers me in such game.

Super fun! But the text does get in the way mid-combo.

This thing is so fun. My best was 17, better than 94% :)

Good fun, my highest was 30, it took a while!

Brilliant game. Thank you so much for this.

56 Stars Better than 100% of players

Git rekd nerds

This is pretty cool, Great stuff!

Maybe having some saves?

Super cool, super addictive :-)

This is great. Very addicting.

allow me to use space and not click!!!!

I don't like the game. The sounds. The way movement flows. Also the game loop is slow after I lose or realize I'll lose.

Paste this bad-boy into your console and watch the real expert play:

(function () { "use strict";

  // ── CONFIG ──────────────────────────────────────────────────
  const AUTO_RESTART = true;
  const RESTART_DELAY = 800;   // ms before auto-restart after death
  const MUTE_SOUND = true;     // silence during autoplay
  const SIM_FRAMES = 350;      // max frames to simulate per check
  // ────────────────────────────────────────────────────────────

  let running = true;
  let totalGames = 0;
  let botBest = 0;
  let scores = [];

  if (MUTE_SOUND && typeof snd !== "undefined") snd = false;

  function wouldHitTarget() {
    if (st !== 1 || !bl || !bl.orb) return false;

    var targets = [];
    for (var i = cWI + 1; i < Math.min(wl.length, cWI + 3); i++) {
      if (wl[i] && !wl[i].caught) targets.push(wl[i]);
    }
    if (targets.length === 0) return false;

    var ta = bl.angle + bl.dir * Math.PI / 2;
    var nw = wl[cWI + 1];
    var spd;
    if (nw) {
      var ddx = nw.x - bl.x, ddy = nw.y - bl.y;
      spd = Math.max(4.5, Math.min(7.5, Math.sqrt(ddx * ddx + ddy * ddy) * 0.038));
    } else {
      spd = 5.5;
    }

    var x = bl.x, y = bl.y;
    var vx = Math.cos(ta) * spd;
    var vy = Math.sin(ta) * spd;

    for (var f = 0; f < SIM_FRAMES; f++) {
      vy += 0.06;
      vx *= 0.995;
      vy *= 0.995;
      x += vx;
      y += vy;

      for (var t = 0; t < targets.length; t++) {
        var dx = x - targets[t].x, dy = y - targets[t].y;
        if (Math.sqrt(dx * dx + dy * dy) < targets[t].radius + 20) {
          return true;
        }
      }

      if (y > 2500 || x < -400 || x > W + 400) return false;
    }
    return false;
  }

  function autoRestart() {
    if (st !== 2) return;
    var go = document.getElementById("game-over");
    var rp = document.getElementById("revive-popup");
    if (go) go.classList.add("hidden");
    if (rp) rp.classList.add("hidden");
    document.getElementById("pause-btn").style.display = "flex";
    document.getElementById("sound-btn").style.display = "flex";
    st = 1;
    init();
  }

  function tick() {
    if (!running) return;

    if (st === 0) {
      handleTap();
    } else if (st === 2 && AUTO_RESTART) {
      totalGames++;
      scores.push(sc);
      if (sc > botBest) botBest = sc;
      console.log(
        "Game #" + totalGames +
        " | Score: " + sc +
        " | Jumps: " + jmp +
        " | Combo peak: " + cc +
        " | Bot best: " + botBest
      );
      setTimeout(autoRestart, RESTART_DELAY);
      setTimeout(function () { requestAnimationFrame(tick); }, RESTART_DELAY + 50);
      return;
    } else if (st === 1 && bl && bl.orb) {
      if (wouldHitTarget()) {
        release();
      }
    }

    requestAnimationFrame(tick);
  }

  window.stopBot = function () {
    running = false;
    console.log("Bot paused. Call startBot() to resume.");
  };

  window.startBot = function () {
    if (running) return;
    running = true;
    console.log("Bot resumed.");
    requestAnimationFrame(tick);
  };

  window.botStatus = function () {
    var avg = scores.length
      ? (scores.reduce(function (a, b) { return a + b; }, 0) / scores.length).toFixed(1)
      : 0;
    console.log(
      "Games: " + totalGames +
      " | Best: " + botBest +
      " | Avg: " + avg +
      " | Running: " + running
    );
  };

  console.log("=== STARFLING AUTO-PLAYER ===");
  console.log("Controls: stopBot() | startBot() | botStatus()");
  requestAnimationFrame(tick);

})();

Fun game, though a difficulty of playing it on a phone is your primed finger gets in the way of seeing the ball!

Love this! Only request is don't display Godlike etc where you are because I've found when it comes up, you can't see where you are and so miss the next first-chance

The single HTML file as a distribution format is really underrated. No server, no CORS issues, no CDN — just open the file. It works offline, you can email it, and it'll still work in 10 years.

I ship self-contained HTML files for a different project and the sneakiest gotcha is </ sequences inside inline <script> tags — the browser sees </ and tries to close the script tag prematurely. You have to escape them as <\/. Curious if the author ran into that one.

Fun concept for the format too — games are the perfect use case.