Usually (in my humble experience) the game design compagnies simply lack the awareness. In that case, one or two email should be enough. Simply state in the email: 1. The number of people that would be able to play the game extra if they put in a certain accessibility feature. (back it up with some source) 2. The way they should implent the feature.

I would suggest something like this (but more formal and friendly and longer, hehe):

Dear [game design compagny],

I tried playing your recent game [insert name here], but I failed to do so because it lacked a very simple and basic accessibility feature. I have [this handicap] and [this many] people also, see [source]. All those people could enjoy your game if you would have but in [this feature]. I hope you will think of me and all the other people in my community, that I will ofcourse see to that your game is accessible if it is, next time *wink wink*, the next time you create a game. You might even add the feature to your downloadable content patch via X-Box live, that would really make my day (and than I won't have to refund the game. That would be awsome).

Or something like that.

I can't write an email like that because I don't have experience with playing games with just one hand, but if it has good sources than I would be more than willing to sign the email for you with my name and email, and I think allot of other people here would to. If you intend to write such a mail and have it singed with allot of names and emails than I suggest asking around for support on other game accessibility forums to.