Can you give more details of just how imeangame "loads itself" (every time Opera starts up, periodically "out of the blue", when you visit certain websites, etc)? Also, when it does appear, does it 'hijack' a desired page or open a new tab? If you examine your Opera extensions, are there any there which you don't recognize? Finally, does this only occur with the Opera browser (and not with a different browser)? Also, under Opera's Settings > Advanced > Privacy & Security, try checking the Browsing history, Download history, Cookies and other site data, Cached images and files, and Hosted app data boxes > Clear data.
