How about...
In all seriousness, a video game—and a TV series—based on the Mirage version of TMNT would kick major shell; I want to see that more than the umpteenth remaster or remake of [insert name of video game here].
Also, not sure about the developer, but I've always been interested in a video game based on the movie "9" and "The Iron Giant", the WB show "Supernatural", as well as the Gargoyles cartoon. And yes, I know there's a Gargoyles game for the Genesis, but I'm obviously referring to a modern approach; in fact, going back to Kingdom Hearts, Square Enix and Disney dropped the ball by not including them when they had the chance. If by now the series has a Shibuya and a fictionalized version of San Francisco, then a gritty, grimy version of Manhattan shouldn't be that far-off.
I'd love to see Wayforward make a Metroid game with pixel art. Not an original choice, I know. But I think it would turn out pretty well.
I like WayForward, so it would be interesting to see their take. My caveat would be that Jake Kaufman has to do the soundtrack alongside Grant Henry.
Watching Castlevania on Netflix made me realize how incredible it would be if there was a Castlevania game made by From Software. Not even just From Soft, give it to a company with experience making soulslike games. It just feels like such a great way to explore the Castlevania universe and lore
Well, the Souls games, especially Bloodborne, are basically pseudo-Castlevanias, but an actual Souls-like game using the Castlevania IP would be diabolically good.