Hi there, apologies your having trouble with the web version. You can always try the desktop version if you want to try the game.
A lot of people are experiencing a lot of different things on the web version, due to different browsers. OS's and such. The web version does also have a long load time which I do apologise for, but I haven't found anyone reporting a problem with full screen, but I will look into it.
Thank you for your feedback!