The teaser’s description says it’s an MMORPG, though exact platforms were not provided. Since it does have a TapTap page, presumably it will at least be on mobile devices. The TapTap overview is given as follows:
Kakao Games confirmed the official name of the new project under development as ‘Project Ares (tentative name)’ as ‘Ares: Rise of Guardians (hereinafter referred to as ‘Ares’), and released a teaser site and video.
‘Ares’ is a game with high-quality graphics and colorful action using various equipment. In the near-future worldview, players can utilize the equipment ‘suits’ with various skills and attributes and engage in strategic battles against powerful boss monsters through ‘suit change’. In addition, you can enjoy splendid play that crosses the ground and the sky with the ‘Valkyrie’ that can fly.
That sounds closer to buzzwords and with only a teaser, there’s not much you can really make out of the game at this point. There are plans to launch it within 2022, with more information to be released via the official website. If you are a little intrigued, then stay tuned to said official website.