The below is a bit of a blast from the past for me personally... (gaming geeks
may be interested)
My first job in the games industry (day one) was to work on the 3D engine for a new version of Frogger for Konami (I was a developer at the then named Interactive Studios, which became Blitz Games and - sadly - went under a few months back). The lead platform was actually the N64 and versions were to follow on PS1, PC and Dreamcast. Sadly the N64 version never saw the light of day despite being fairly advanced. However, I did carry on working on the other versions (primarily PC) on the graphics side. The final game that actually came out (Frogger2: Swampy's revenge) was a lot different to some of the concepts we'd knocked up but ultimately our Publisher, Hasbro Interactive, didn't agree with our 'out there' level designs; which were quite impressive back in the day. As a result the game, whilst in 3D, was very 2D in how it played and felt. Shame.
I remember working on a few development carts and one of them sold on ebay for a fair amount of money not so long ago. It is also mentioned in the video below. I actually produced that development build on that cartridge along with the developer debug menus and various options.
It was a very early build hence the animation system and camera systems were fully working at the time.
I have a lot of happy memories of the above and some of the other N64 games the studio worked on, too (which were sadly canned around the same time or shortly after).