As with any good franchise based gacha game, Code Geass Genesic Re;Code has added in the characters from Renya of the Darkness, a spin-off manga, specifically Renya himself and Futaba Sumeragi. For the unfamiliar, Renya possesses a mechanical left arm and has been training in a hidden village to master the arts of ninjutsu. He meets C.C. when the village is attacked and his friends captured, but her attempts to bestow power on Renya devolves into a curse instead.
Code Geass Genesic Re;Code is expected to launch sometime Spring 2021. The official website is hosting a “Challenge from Zero” game, where enthusiasts can endeavour to solve a mystery left by Zero. Hints to solve the mystery will be released weekly, though of course, you can still try to solve it earlier. Participants will need to follow the official Twitter as well, and stand a chance to win 1 million yen, or an illustration from Takahiro Kimura. The prize money will be distributed into 6, with one person getting 500,000 yen and the rest 100,000. Presumably the event has already ended in February with the prizes to be distributed in March, but you can still attempt the puzzle, of which at the time of writing, 992 have solved it. You can try it out here.
Otherwise, official sources have yet to reveal the nature of the gameplay, so stay tuned on that front.