at minimum, a 100% run requires doing the game twice. you could consider the 2nd time a New Game+, since while the areas are the same, the creatures will be slightly different. To beat a 100%, someone merely needs to get all 150 mutations, and you automatically win. The primary problem is that to do so you must also finish the any% run and then continue the game after the credits end.
To do an any% run, you simply need to beat the killer cubivore. to do this, you need to have 100 mutations, at which point you get teleported to the boss rush, and after beating all bosses, you face him (and 4 colored cubivores, I'll have to find out if you need to kill them or not, if not, I'll just attempt to skip them). this is possible on the first play-through, but only if you very carefully choose what to eat and when. on the other hand, if I skip getting 100 by the time I end the first play-through by not going after the more annoying mutations that may cost time, I can get some slightly easier lower-limb count mutations, but to do so might cost me too much time with cut-scenes as well as the loss of a usefull EZ-mutation.
Right now, I'm planning it. since it's a TAS I should never get hit if I don't mean to get hit, so I can ignore killing excess for exp (to increase my stomach, and thus HP), collecting scar points (increased defense), and collecting hump points (to increase the effect of healing). I have to consider whether taking the time to gather horn points for the bonus to attack is worthwhile, both the cubes I can collect and the training stations. There's also the matter of the tounge, which allows eat-n-run, allowing me to sometimes skip the animation for eating (but not always, only really works on weaker creatures, so it might not be worth the time). I also can either choose to collect rejuvinators to allow me to heal at any time, but to need to would be might be seen as sloppy, even if it saved a bit of time.
As for what mutations I take, I have the choice in the end of yellow vs. grey. yellow is slower but stronger than grey, but grey is of course faster yet slightly weaker (they're both the top attackers) more than likely grey. I shouldn't need lovebits if I can correctly manipulate luck to make sure all females (or at least the ones I need) bear children, but to do so, I need a working rom/memory watcher, and the cheat tab supplied with Dolphin doesn't update adresses dynamically, only when you refresh it, so I need a better version.
speaking of luck manipulation, getting a slot token would do wonders there, allowing me to pick exactly what colors I want (though not type sadly), so all the more reason to get a working rom/memory watch.
The actual playing will be rather simple since the camera controls are nice; it has 8 fixed locations around you, so little in the way of figuring out complicated angles to be moving at has to be done (except right after certain cutscenes where the camera moves a bit).
Edit: after thinking about it, I'll be doing a 100% run, but I'll set aside a .dtm that ends after killer cubivore as well, since looking at my plans so far, a 100% run's play-through to 100 mutations is exactly identical to an any% run, so while a 100% run will be longer than an any% run, the first 100 mutations will be the same length of time for both. to facilitate this, I've re-optomized my main menu to format and save to a memory card instead of having no memory card. this'll force viewers to delete their memory card manually before playback, but it shouldn't be an issue otherwise. For minor entertainment (and because I noticed it in the movie rules) I chose an actual name as opposed to "A" because the game isn't enough of a frame war yet to need to lose the entertainment of the character's name. still chose something short though, but it's fitting for the silly game.
almost set to do the actual gameplay, just doing a non-TAS run to get my bearings and make some makeshift maps and layouts to make finding stuff I need easier.
