Script to run doom on Mural.

doom.js

// @ts-check
function delay(ms) {
  return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
}

function avgColor(data, x0, y0, width, height, dist) {
  const color = [0, 0, 0, 0];
  for (let y = 0; y < dist; y++) {
    for (let x = 0; x < dist; x++) {
      const offset = ((y0 * dist + y) * width + x0 * dist + x) * 4;
      color[0] += data[offset + 0];
      color[1] += data[offset + 1];
      color[2] += data[offset + 2];
      color[3] += data[offset + 3];
    }
  }

  color[0] = Math.round(color[0] / (dist * dist));
  color[1] = Math.round(color[1] / (dist * dist));
  color[2] = Math.round(color[2] / (dist * dist));
  color[3] = Math.round(color[3] / (dist * dist));

  return color;
}

var boardId = window.location.pathname.match(/([^\/]+\/[^\/]+)\/[a-z0-9]*$/)[1].replace('/', '.');
var userId = app.me.get('username');

async function createScreen() {
  const TEMPLATE = { "height": 138, "hidden": false, "id": "0-1600259662016", "instruction": "", "locked": false, "lockedByFacilitator": false, "owner": "martingiachetti3508", "parentId": null, "rotation": 0, "stackingOrder": 0, "title": "", "type": "murally.widget.TextWidget", "width": 138, "x": 330, "y": 87, "fontFamily": "proxima-nova", "textAlign": "center", "fontSize": 23, "minLines": 6, "backgroundColor": "#fcfe7d", "textType": "realNote", "bold": false, "italic": false, "strike": false, "underline": false, "text": "", "border": false, "round": false, "create": true, "recover": false };
  const mwidth = 80;
  const mheight = 40;

  const widgets = [];

  const sep = 1;
  const swidth = TEMPLATE.width;
  const sheight = TEMPLATE.height;
  for (let y = 0; y < mheight; y++) {
    for (let x = 0; x < mwidth; x++) {
      widgets.push({
        ...TEMPLATE,
        x: x * (swidth + sep),
        y: y * (sheight + sep),
        id: `pixel-${x}-${y}`,
      });
    }
  }

  for (let i = 0; i < widgets.length / 50; i++) {
    const widgetsMap = widgets.slice(i * 50, (i + 1) * 50).reduce((acc, w) => ({ ...acc, [w.id]: w }), {});
    // post to mural
    const authorization = `Bearer ${window.app.getToken().jwt}`
    const [, , , , workspace, muralId] = location.pathname.split('/');
    const url = `https://app.mural.co/api/v2/murals/${workspace}/${muralId}?acceptBadRequest=true`
    await fetch(url, {
      "headers": {
        "accept": "application/json",
        "accept-language": "en-US,en;q=0.9",
        authorization,
        "cache-control": "no-cache",
        "content-type": "application/json; charset=utf-8",
        "pragma": "no-cache",
        "sec-fetch-dest": "empty",
        "sec-fetch-mode": "cors",
        "sec-fetch-site": "same-origin",
        "x-mural-ly-version": "1.0.0",
      },
      "body": JSON.stringify(widgetsMap),
      "method": "POST",
      "mode": "cors",
      "credentials": "include"
    });

    await delay(2000);
  }
}

async function updateScreen() {
  const mwidth = 80;
  const mheight = 40;

  const widgets = [];

  const sep = 0;
  const swidth = 138;
  const sheight = 138;
  const x0 = 138 * 20;
  const y0 = 138 * 20;
  for (let y = 0; y < mheight; y++) {
    for (let x = 0; x < mwidth; x++) {
      widgets.push({
        backgroundColor: '#ffffff',
        x: x0 + x * (swidth + sep),
        y: y0 + y * (sheight + sep),
        id: `pixel-${x}-${y}`,
      });
    }
  }

  const sliceSize = 5000;
  for (let i = 0; i < widgets.length / sliceSize; i++) {
    const widgetsMap = widgets.slice(i * sliceSize, (i + 1) * sliceSize).reduce((acc, w) => ({ ...acc, [w.id]: w }), {});
    // post to mural
    const authorization = `Bearer ${window.app.getToken().jwt}`
    const [, , , , workspace, muralId] = location.pathname.split('/');
    const url = `https://app.mural.co/api/v2/murals/${workspace}/${muralId}?acceptBadRequest=true`
    await fetch(url, {
      "headers": {
        "accept": "application/json",
        "accept-language": "en-US,en;q=0.9",
        authorization,
        "cache-control": "no-cache",
        "content-type": "application/json; charset=utf-8",
        "pragma": "no-cache",
        "sec-fetch-dest": "empty",
        "sec-fetch-mode": "cors",
        "sec-fetch-site": "same-origin",
        "x-mural-ly-version": "1.0.0",
      },
      "body": JSON.stringify(widgetsMap),
      "method": "POST",
      "mode": "cors",
      "credentials": "include"
    });

    await delay(2000);
  }
}
// updateScreen()

function updateColor(widgetId, color) {
  // const boardId = window.location.pathname.match(/([^\/]+\/[^\/]+)\/[a-z0-9]*$/)[1].replace('/', '.');
  // const userId = app.me.get('username');

  const operation = {
    boardId,
    operation: {
      boardId,
      action: 'UPDATE_WIDGET',
      userId,
      widgetId,
      validatePayload: false,
      values: {
        backgroundColor: color,
      }
    },
  };
  // send remote
  // _socket.emit('broadcastP2P', JSON.stringify(operation));
  // send local
  // _socket._callbacks.$remoteOperations[0](JSON.stringify(operation));
  // const w = window.engine.widgets.get(widgetId);
  // window.engine.widgets.update({ ...w, properties: { ...w.properties, backgroundColor: color } });
  return operation;
}

function setPixel(x, y, color) {
  return updateColor(`pixel-${x}-${y}`, `rgb(${color[0]},${color[1]},${color[2]})`);
}

function clearScreen(color) {
  const mwidth = 80;
  const mheight = 40;
  for (let y = 0; y < mheight; y++) {
    for (let x = 0; x < mwidth; x++) {
      setPixel(x, y, color);
    }
  }
}

async function initDoom() {
  let iframe = document.querySelector('#doom_iframe');
  if (!iframe) {
    iframe = document.createElement('iframe');
    iframe.id = 'doom_iframe';
    document.body.appendChild(iframe);

    iframe = document.querySelector('#doom_iframe');

    const ibody = iframe.contentDocument.body;

    const div = document.createElement('div');
    div.id = 'dosbox';
    ibody.appendChild(div);

    let script = document.createElement('script');
    script.type = 'text/javascript';
    script.innerHTML = await (await fetch('https://code.jquery.com/jquery-3.5.1.slim.min.js')).text();
    ibody.appendChild(script);

    script = document.createElement('script');
    script.type = 'text/javascript';
    script.innerHTML = await (await fetch('https://js-dos.com/cdn/js-dos-api.js')).text();
    ibody.appendChild(script);

    script = document.createElement('script');
    script.type = 'text/javascript';
    script.innerHTML = `
          var dosbox = new Dosbox({
            id: "dosbox",
            onload: function (dosbox) {
              dosbox.run('https://js-dos.com/cdn/upload/DOOM-@evilution.zip', "./DOOM/DOOM.EXE");
              //dosbox.run('https://drive.google.com/uc?export=view&id=1XVOF8ktihBL-RP0vqGZMBMC1dpdCfXHZ', "./DOOM/DOOM.EXE");
            },
            onrun: function (dosbox, app) {
              console.log("App '" + app + "' is runned");
              const canvas = $('.dosbox-container canvas')[0];
              const ctx = canvas.getContext("2d");

              const cwidth = 640;
              const cheight = 320;
              setInterval(() => {
                console.time('frame');
                const img = ctx.getImageData(0, 0, cwidth, cheight);
                window.top.postMessage({cmd: 'frame', data: img.data}, '*');
              }, 50);
            }
          });
          $(".dosbox-start").click();
        `;
    ibody.appendChild(script);
    await delay(10000);
  }
  screenCastRun();
}

function screenCastRun() {
  const cwidth = 640;
  const cheight = 320;
  const downscaleFactor = 8;
  const mwidth = cwidth / downscaleFactor;
  const mheight = cheight / downscaleFactor;

  window.onmessage = function (e) {
    if (e.data.cmd === 'frame') {
      console.time('frame');
      const data = e.data.data;
      const operations = [];
      for (let y = 0; y < mheight; y++) {
        for (let x = 0; x < mwidth; x++) {
          const color = avgColor(data, x, y, cwidth, cheight, downscaleFactor);
          operations.push(setPixel(x, y, color));
        }
      }
      console.timeEnd('frame');
      console.time('render');
      const widgets = operations.map((o, i) => {
        const w = window.engine.widgets.get(o.operation.widgetId);
        const color = o.operation.values.backgroundColor;
        const nw = { ...w, properties: { ...w.properties, backgroundColor: color } };
        return nw;
      })
      window.engine.widgets.update(...widgets);
      console.timeEnd('render');
    }
  };
}

var _renderParams = {
  x0: 100,
  y0: 100,
  scale: 1,
};
function screenCastRun2() {
  const cwidth = 640;
  const cheight = 320;
  const downscaleFactor = 4;
  const mwidth = cwidth / downscaleFactor;
  const mheight = cheight / downscaleFactor;

  const canvas = /** @type {HTMLCanvasElement}  */(document.querySelector('.render-engine'));
  const ctx = canvas.getContext("2d");
  const w = canvas.clientWidth;
  const h = canvas.clientHeight;
  // clearColor
  ctx.fillStyle = '#dddddd';
  ctx.fillRect(0, 0, w * 2, h * 2);

  window.onmessage = function (e) {
    if (e.data.cmd === 'frame') {
      console.time('frame');
      console.time()
      const data = e.data.data;
      // clearColor
      ctx.fillStyle = '#dddddd';
      ctx.fillRect(0, 0, w, h);
      for (let y = 0; y < mheight; y++) {
        for (let x = 0; x < mwidth; x++) {
          const x0 = _renderParams.x0;
          const y0 = _renderParams.y0;
          const scale = _renderParams.scale;
          const dp = 138
          const sep = 1
          const color = avgColor(data, x, y, cwidth, cheight, downscaleFactor);
          const c = `rgb(${color[0]},${color[1]},${color[2]})`;
          ctx.fillStyle = c;
          ctx.fillRect(x0 + x * (dp + sep) * scale, y0 + y * (dp + sep) * scale, dp * scale, dp * scale);
        }
      }
      console.timeEnd('frame');
    }
  };
}

async function run() {
  if (!window.engine.widgets.get('pixel-0-0')) {
    await createScreen();
    await delay(2000);
  }
  initDoom()
}

run()

To RUN

just paste it on a developer console after an empty mural is loaded