A random dungeon generator that fits on a business card (2019)(gist.github.com)

    w=(╱ ╲);while :;do echo -n ${w[RANDOM%2]};done

    #define l(a, b, c, d) for (int y = a; y < b; y++) for (int x = c; x < d; x++)

  for (let y = u - 1; y < u + h + 2; y++) {
    for (let x = t - 1; x < t + w + 2; x++) {
      if (m[y][x] === ".") return;
    }
  }

  let d = 0;
  let e, f;

  if (!s) {
    for (let y = u - 1; y < u + h + 2; y++) {
      for (let x = t - 1; x < t + w + 2; x++) {
        const s = x < t || x > t + w;
        const v = y < u || y > u + h;

        if (s ^ v && m[y][x] === "#") {
          d++;
          if (g(d) === 0) {
            e = x;
            f = y;
          }
        }
      }
    }
    if (d === 0) return;
  }

  for (let y = u - 1; y < u + h + 2; y++) {
    for (let x = t - 1; x < t + w + 2; x++) {
      const s = x < t || x > t + w;
      const v = y < u || y > u + h;

      m[y][x] = s && v ? "!" : s ^ v ? "#" : ".";
    }
  }

  if (d > 0) m[f][e] = g(2) ? "'" : "+";

  for (let j = 0; j < (s ? 1 : g(6) + 1); j++) {
    m[g(h) + u][g(w) + t] = s
      ? "@"
      : g(4) === 0
      ? "$"
      : String.fromCharCode(65 + g(62));
  }

  for (let j = 0; j < 1000; j++) {
    cave(j === 0);
  }

  for (let y = 0; y < H; y++) {
    let row = "";
    for (let x = 0; x < W; x++) {
      const c = m[y][x];
      row += c === "!" ? "#" : c;
    }
    console.log(row);
  }