"We have Unity working," Musk told McCaffrey, and noted that they also have a "beach buggy driving game, Dune Buggy, or something like that, that's pretty fun. Then Cuphead, we've got working." He says that the game's developers have been helping to get it working, and that "it's a cool game, it's insanely difficult."
Musk went on to speak about some of the challenges that they've been facing, namely, storage size: "We didn't anticipate having all these games there, so storage space will be a tricky one," he says. "So you might have to decide what game you want to play, then it will download. So if you want to play other games, delete that one and download another one."
McCaffrey followed up with Cuphead developer Maja Moldenhauer, who indicated that Tesla reached out to her and her team to port the game, and that the only stipulation was that the game had "to play super, super clean... and that it had to control precisely." It apparently requires a USB controller to use, rather than with the car's touchscreen. It sounds as though Tesla's aiming for "targeting a release date of later this summer," and drivers will only be able to play the "Inkwell Isle One section of the game, due to the storage limitations."
