Add game with a nasty bug

.github/workflows/build.yml

@@ -0,0 +1,37 @@
+name: Compiling CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      - name: Configure pages
+        uses: actions/configure-pages@v4
+      - name: Install devbox
+        uses: jetpack-io/devbox-install-action@v0.7.0
+      - name: Build app
+        run: devbox run deploy
+      - name: Upload artifacts
+        uses: actions/upload-pages-artifact@v3
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    needs: build
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4

README.md

@@ -1,6 +1,15 @@
-# Umbra
+# Compiling
 
-This is an app written in elm, deployed at [carlotm.github.io/umbra](https://carlotm.github.io/umbra/).
+When I was a child, my sister showed me this puzzle,
+it's a silly game to play while compiling (https://xkcd.com/303).
+
+Warning: I don't know if the puzzle actually has a solution.
+
+Rules are:
+
+- Move the cursor with `hjkl` or arrow keys
+- `space` to put a value in the current cell
+- Put the next value horizontally or vertically skipping 2 cells or diagonally skipping 1 cell (the UI will help finding the possible moves)
 
 ## Local development