Since email evolved from physical letter writing, the most formal emails follow the rules from formal letter writing. As Max mentioned in his comment, use the rules for formal letters to make your email formal.
You can probably skip the date and full address from paper letters since this is included in email metadata, but start with a salutation of the full name of the person or use 'Sirs:' or 'Dear Sirs:' if addressing a group of people. If your letter represents a company or group of people use 'we' but if only yourself use 'I'. Finish with your full name, title/company, and contact info.
The best letters are short and to the point, and give the reader some reason to cooperate. If your non-English site were for example German, you might include the sentence "We are excited to give our German readers information about your game.' This tells them that in return for cooperation with you they will be able to sell more copies of their game to a market segment that otherwise might never hear of them.