re: unreleased games
That powerline game (Den-sen) was being made at SCEI by a weird amalgam of people, primarily Ape Escape people IIRC. The creator of Umihara Kawase, Kiyoshi Sakai, was one of the leads–I asked him about it once and he said it was shown off way too early in lieu of there being anything else to show for PS2, and that it didn’t last much longer after being announced because nobody really knew what they were trying to make. That same team ended up making Mr. Mosquito, I think? and Sakai ended up leaving the industry for a while afterwards.
The Kimba game was a passion project for Nintendo inasmuch as they wanted to collaborate with Tezuka Productions on a game project, with the expectation that Tezuka’s people (specifically Osamu Tezuka’s son, whose name escapes me at the moment) would be co-directing and working on the game on a genuine, regular basis, and so when that guy ended up flaking on them they killed the game. My recollection is that Miyamoto’s right-hand Takashi Tezuka (no relation to the manga dynasty) was running point on Kimba, but I could be wrong.
As for games I’d like to see… Shigesato Itoi was making an original N64 game code-named “Cabbage” that, to my knowledge, didn’t make much progress and eventually coalesced into Hey, You! Pikachu!, but I’d really like more details.