Sega has announced four new games for smartphone and tablet that are coming in time for Christmas or just into the new year. And two of them feature the publisher's biggest star.Sonic & All-Stars Racing Transformed for iOS and Android will be the mobile equivalent of the console game out for a while. It takes the original Sonic & All-Stars Racing concept, in which you could zip about in vehicles specific to a number of big Sega properties, and adds sea and air elements to tracks. The vehicles, therefore, transform into boats and planes when needed and offer different gameplay mechanics for each.In addition, Sonic the Hedgehog 2 has been remastered for a new mobile release. Owners of an iPhone, iPad or iPod touch will already have had access to a bit-by-bit version of the game previously, but this one has been given a definitive update. It will sport upgraded visuals and remastered audio. And what's more, Sega will be pushing it as a free upgrade for those who bought the standard version. It will be the first time the game has been available on Android.The other two games on the schedule are for iOS only. Demon Tribe blends multiplayer online battle arena (MOBA) elements with card collecting and action-RPG gameplay. It has been devised by Masayoshi Kikuchi, who previously worked on Panzer Dragoon and Jet Grind Radio.Rhythm Thief & the Paris Caper is a "toe-tapping rhythmic adventure" and is not due for release until early 2014.The other three games will be available in "winter", with the remastered Sonic the Hedgehog 2 being given a more specific "November" release date.