wait, what? I understand the want for arguments to be passed to the game if you use a launcher. steam has this and I think i even used it once or twice, but can't remember why. Just saves you hte hassle of creating a custom link to the app with the options. Games should not need this by design. Though it might be needed for some troubleshooting options.
But html games? a command line option?
I think what you really want is this:
an option to launch web games from the app with external browser, instead of the built in browser.
you would not have access to the save game that was made in the built in browser or want features of your regular browser.