For exporting to html5, set 'Canvas Resize Policy' to 'Project'. This prevents the browser from showing outside the viewport boundaries.
Aside from that, running the project will give this error:
Error
The following features required to run Godot projects on the Web are missing:
Cross Origin Isolation - Check web server configuration (send correct headers)
SharedArrayBuffer - Check web server configuration (send correct headers)
To fix this, Fernando Gimenez provided a python script. Run server.py with python server.py.
Then, through http://localhost:8000/build/flappybird.html (assuming there is a build folder and an exported html file), you can access the game.
Alternatively, you can go to localhost:8000 and navigate to the built html file to load it.
- Move with 'Space' or 'Left-Click'
- Select options with 'Left-Click'
- Textures from Samuel Custodio
- Thanks to the community for providing a guide, tutorial and documentation, which I frequently referenced.