All of these titles got new trademarks a few days ago.
During The Game Awards last week, Sega had a pretty impressive line of announcements as they confirmed that no less than five frequently requested classics was going to get new installations at some point in the future. Just one day later, they also revealed that this is only the beginning, and that the intention is to bring even more classics back.
Fast forward until today, and Gematsu has now noticed that Sega has trademarked more older games, including Altered Beast, Eternal Champions and Kid Chameleon.
