Things are going crazy. First of all, someone found "official Yume Nikki posters"
https://www.reddit.com/r/yumenikki/comments/7mail5/official_yume_nikki_posters_spotted/
Everyone is still skeptical of the posters because it happened out of the blue. Apparently Kadokawa is behind these posters. (Kadokawa owns Enterbrain, who created RPG Maker.) The Yume Nikki light novel was also relicensed.
Then a countdown appeared. (https://promo.kadokawa.co.jp/gamecountdown/) It seems to be an official Kadokawa website. Someone on reddit translated the site description, and it reads: The game 'YUMENIKKI -DREAM DIARY- (ユメニッキ �ドリームダイアリー）' is going to be released soon.
I'm confused. It's been 10 years of complete and utter silence, and now, all of a sudden, so many things are happening. The light novel was relicensed, posters were spotted, the game was released on Steam, and now there's a countdown. At the time of writing this, the countdown is at 13 days, 23 hours and 30 minutes. I'm guessing it's going to be a new game (the URL for the countdown says /gamecountdown/ so that was a complete giveaway.)
PCgamer covered it here: http://www.pcgamer.com/yume-nikki-the-surrealist-cult-classic-adventure-game-about-dreams-is-out-now-on-steam/