Legal issues differ from country to country, most international storefronts address those issues and problems to you before even publishing. Such as google play saying you need X cerdental such as some places requiring a rating system approval and rating based off a standard service most of which isn't worth selling to unless you have a game that supports multi-language, some cost money so yeah not worth it.
Most of the legal issues is more or less a personal prefference of what you want to expect from the users other than liablity claims of loss data or damaged hardware, which basically are just put in some EULA's to prevent people from blaming them for hardware or software issues more than likely caused by the OS. Some places require that you address certain issues like the usage of cookies but all you have to say is cookies use & collect browser data for advertisement agencies and done if you do ads.
Which you can easily address in a user licence agreement. If you sell it through certain storefronts they make you use their standard template EULA, such as scirra so you won't have to worry about anything if you sell it through them. But for the most part you won't have to worry about google play, steam, amazon, or most of the popular storefronts either.