Sega has released a free 8-bit Bayonetta game on Steam last weekend. The game features typical 8-bit platformer gameplay mechanics.
The company did not comment on why it chose to release an 8-bit Bayonetta game on Steam but it is likely that it will be used to promote an upcoming Bayonetta franchise announcement.
The game contains references to a webpage hosted on Sega's domain that counts down to April 11th 2017. It is likely that Sega will announce the PC version of the game as the original was only available on Xbox 360, PlayStation 3, and Wii U.
Whether the game can actually be categorized as 8-bit title is questionable because the game seems to feature 16-bit graphics instead.