As of December 08, 2020, Nintendo of America Inc.’s trademark filing, US Serial Number 79289925, Eternal Darkness, has been registered with the United States Patent and Trademark Office .Originally filed May 14, 2020, however claims priority from international registration 1541696A originally filed January 15, 2020.
The major difference between this filing and previous filings by Nintendo and one that is of note, is that this is an actual registration and not a Request for Extension of Time to File a Statement of Use. The later is what was done many times in the past, but is not the case here.
While a trademark application is not evidence of a game being developed, it is interesting to observe still.