is there any way to play the full version on a browser? My son uses my computer, and I don't want him to see it :)
use a virtual machine with a password or make a separate user for yourself. You can also simply hide it, in a folder where he won't find, and rename the executable to "forever.hgp" so even if he tries to open it, it won't work.
If you want to leave no trace, I recommend a virtual machine with a password. Use VirtualBox.