I don't want any developers stealing my ideas again like they did with Smash Bros so I'm not going to make a serious comment. But seriously, why hasn't anyone made Hyperdimension Neptunia Kart yet? It's like they don't want my money. They could call it Racerdimension Neptunia or just Nep Kart.
I'm not even joking, it'd probably sell to the niche that buys these games. To really mess things up they could make it the best game in the genre so when people are arguing about CTR vs Mario Kart they'd suddenly cringe as they remember that Neptuni R was objectively better.