Knowledge of English at Upper-Intermediate level or higher, because English is the language we most often use for communicating with clients.
It's also awesome if you keep up with the gaming industry, whether you actively play or are just enthusiastic about games. So, for example, you can tell the difference between an MMORPG and a Hidden Object game.
No experience in sales is required. Your eagerness to grow in sales and the gaming industry is enough for us to consider your application.