A game can now be "modal". This means it will request for pointer locking on click.
The JSON specification for sprite's animation has changed allowing to provide a duration in seconds for each frame. There was a few little quirks in the way the resizing was handled when the game resolution changed. It is is still more complex than I wish but it all works well for the user.
The problem was the amount of varying variable used in that shader. Since in Windows, WebGL goes through ANGLE, it is likely that it cannot support as many variables. Anyway, it is all good since a lot of these variables should have been made exposed as uniforms in the first place.