(Full disclosure: I was searching my browsing history to make sure I didn't steal this idea from someone else, and amid all the YouTube videos of Japanese people playing piano covers of Mario songs, I found this Reddit thread by cm097. It's not exactly the same concept, but I don't like websites that just take articles from other websites without crediting them, so consider yourself credited, cm097.)
When you saw the words "Mario Kart meets GTA," many of you instantly pictured Mario murdering pedestrians by jumping on them or running over mushroom people with a coupe, but that's not what I mean. The best aspect of the GTA series for me isn't the part where you can blow up stuff with a bazooka, but the fact that you have a massive city to explore at your leisure while occasionally running into insane Easter eggs.
"Whoa. That's crazy. Let's blow it up with a bazooka."
Meanwhile, one of my favorite things about the Mario Kart series is that the stages are secretly linked -- as GameXplain points out, if you take your eyes off the road in Mario Kart: Double Dash, you can actually see landmarks from other tracks as background details, suggesting that the entire game is set in a vast interconnected world. For instance, Peach's Castle can be seen from Mushroom Bridge:
"Stop-a here and hand me the binoculars, she's-a getting into the shower. Mamma mia!"