Let’s kick off this experiment with a game I call:
Brain Bug
Overview: You play the game as a Brain Bug, a tiny bug who can crawl inside other creatures and control their actions. Third person perspective, 3D world. It’s Being John Malkovich meets Shadow of the Colossus. It’s not really, but that sounded too funny not to write.
You navigate as a tiny bug in a bug-scale world, where a pile of dirty clothes is a mountain, a dropped peanut a feast. You run around in this world until you can jump in the ear of a larger creature.
Once inside, you now control that creature, and your scale shifts. As a dog, you can do things at dog-scale, and can use special dog-skills like bark and pee-on-things.
At each scale, you are manipulating the environment to set-up your next jump. As the bug, you are platforming to get up to the couch where the dog is sleeping, so you can jump in her ear.
As the dog, you are trying to make enough noise to get the owner to let you out of the house, and so on.
Now, these things need some kind of goal, so: You watch TV when the owner of the house falls asleep, and you’ve fallen in love with the Channel 42 Newswoman. Your goal is to hijack your way across town, make your way to the TV station and pitch some woo. It’s Grand Theft Auto meets Broadcast News. [can't...resist...spurious...comparisons!]
The key element of the game is the kind of powers-of-ten change when you shift to the scale of larger creatures, and a familiar landscape pulls out to reveal new opportunities and challenges.
As a Brain Bug, you could control basic motor functions of your hijackees, but some of the higher functions are set to cruise control. So you could walk around as a human, pick things up and set them down, but you would have no idea how to drive a car or operate an elevator.
Hijinks ensue!

You may be interested to know that a puzzle game called “Space Station: Silicon Valley” was available for the Nintendo 64. It didn’t do exactly what you have suggested here, but playing involved controlling a microchip running around taking control of animals. The microchip used to be part of a robot which broke during a failed landing attempt on the space station, hence the need for bodies to inhabit.
There were 4 climates (temperate, icey, jungle, and desert), each with a variety of animals which could be controlled. Each climate had a handful of levels, each with different goals (involving getting bits the ship I think) and animals to accomplish them with (each animal had different skills – one of the foxes could teleport, sheep could float, etc).
I’ll have to see if I can track that one down (and my N-64, for that matter).
As much as it pains me to know that not every one of my ideas is a new thing under the sun (ha-ha), it great to see a game built around similar ideas…it’s like getting a prototype for free.
There is a tendency in creative industries to get very married to an idea. Part of the idea behind Design-A-Day is to pump out enough ideas to begin to get some emotional distance from the ideas so that it is easier to be self-critical of them.
Thanks for the tip!