After cloning:

npm install -g hexo-cli
npm install

hexo server

hexo new post "Hello World"

npm run deploy

Tracer is already set up this way, so it's a good example. Here's how I added Tracer.

Make a directory and copy the game/demo into it.

mkdir source/tracer
cp -r $TRACER_DIR/src/* source/tracer

Then tell hexo not to process those files:

1. editing _config.yml
2. find the skip_render section
3. add - "tracer/**/*"
4. delete db.json if hexo refuses to build after this

The game should now be available at the /tracer path.