Concept art for it was later leaked online on 2014 in a portfolio for Next Level Games belonging to artists Nelson "Dedos" Garcia and Xochitl. The concept art indicated a more angular style, and contained art for Samus as well as a Boss Creature.
An Iwata Asks interview previously mentioned the prototype without revealing it was Metroid:
Iwata: What was your impression at Next Level Games when you first heard about this project?
Bryce: At the time, we were actually involved with a completely different project for Nintendo, and one day we had a video conference about that.
Chad: We had made a prototype in preparation for that meeting.
Bryce: And Kensuke Tanabe-san suddenly started something like a drumroll and said, "You're gonna make Luigi's Mansion 2!" I was so surprised I could barely speak.
In January 2015, details surfaced of a cancelled Metroid game that may be related to this project. A source for Unseen64 revealed that that game was intended to have a different art style from previous Metroid games. A 30-second prototype video that has not been released showed Samus blasting her way through enemies before confronting a boss resembling Kraid.