I've thought about that, and experimented a little. once again, the physics get in the way.
Holding two different direction buttons at once doesn't do anything too useful, so no good left+right or up+down glitches.
I'd love for there to be some input/cancellations that makes Sonic come to a complete stop. I only know of one, the orange shield power up that can make you dive downwards, canceling all X/Y speed. But that shield does not appear everywhere, and even then is out of the way of the fastest route. (edit: I just watched volcanic valley 2. There is an orange shield on the way :-P)
When they introduced the 3D element, they removed the 'polar grid' of Sonic's 8 directions. Sonic may have 8 directional movements, but his movements are not just limited to those 8 directions, they very often steer off course. That sounds complicated, so let me explain.
The turning in the game is very counterintuitive. When sonic is in a complete standstill, if you hold the direction he is facing, he will run forwards in that direction. However (and what makes this game incredibly difficult) his turning does not work the same way as other 3D games. if you start turning to Sonic's right or left, he will make a wide arc until he eventually is going to intended direction.
When it comes to making 180's, he sucks.
(lame drawing, but just to get the idea across.)
If you are holding up, then let go and start pressing down, Sonic will spin around on his right leg as a pivot, swing around and do a 180, then start accelerating in that new direction. he will now be lateral with the first direction he was facing, except displaced to the left/right. He will *literally* do a U turn, and not go the opposite direction on the direct path that he just came from, which is why the game is so difficult to play. When you are at average speeds, and trying to collect something small, like a Flickie, you will run towards it, overshoot, turn around to get back, but you're turning puts Sonic on a new trajectory, and you try to re-compensate, but that makes Sonic miss again and he has to turn around, etc. etc. etc. In real time, it can take me 10+ seconds to get a Flickie.
This is what it looks like trying to catch one Flickie in the center of the field:
Even when in a standstill, pressing a direction for 1 frame does not turn Sonic completely in that direction. You have to hold it 3-4 frames, and his X/Y positions will have changed in the same U turn style as if running (pivoting around his foot), so I have to take that into account too.
Now, complete halt? here's where it gets even more tricky.
The best idea to come to a halt is to *brake* by holding the opposite direction, right? This unfortunately causes the U turn problem that I mentioned earlier. I could be heading straight at a robot, do a U turn before I hit him, start to dash to kill the robot, and by the time I've stopped, I'm about 5 feet away from where the Flickie lands in a direction I was never even pressing. I have to test all sorts of unorthodox angles/braking techniques in order to get that dead-halt right after I hit a robot, and usually that does not work so well.
But, knowing what I know now, here's what I would *like* to happen (and some things that I to not work:)
-rolling is very bad, when your intent is to make sudden stops. when rolling, Sonic usually likes to keep rolling, even if his speed is very slow, and he hates turning (this applies to spin dashes too. These are both forms of rolling that are very straight sensitive; when you start to turn, your speed starts dropping). what is most aggravating is you can only charge a spindash when you are completely stopped, and going from a roll to a complete stop requires braking and losing speed about 10-20 frames before my intended target. I can be going at a speed of 10, press B, and Sonic will curl and roll slowly forwards at snail pace, not charging up a spindash. (Pressing A/C will make him jump.)
-Jumping cancels all roll/spindash effects, so my guess is that jumping might be the key here to quick stops. But the jumps are just as quirky as Sonic's running movements, so jumping and ending up where you want to be are two completely different things, especially when not jumping in a straight line.
-"braking"- i.e. holding opposite directions so that I decelerate enough when I reach the robot- works sometimes, I'll start a roll one frame before I hit a robot, and 10 frames before that I'd have been holding the opposite direction. Sonic usually overshoots the landing spot of the Flickie, and I have to adjust even more to compensate.
So I suppose that I just have to watch SprintGod's videos closer (he makes many major mistakes in Flickie collecting; sometimes the slipperiness gets the better of him and he loses 1-3 seconds, other times he is spot on and loses no time in jumping, collecting, and running to the next destination), and at each robot test to see what is the most optimal way to slow down and either stop for a spindash to the next destination, or to jump and start running there (as I did for the most part in my WIP.) In my revised WIP, I've so far gotten 2 successful stop/spindash/collect Flickies done, which is good.
But I like your idea of mentioning *now* of exploiting the game engine to create instant stops at high speeds, which the other sonic games offer, but I think this game is just too slippery and the controls built to resist such beneficial movements.
Difficult!
ok I'm done. The game is tough to play. However, it probably will be easy to optimize now that I have the speed value, and already know where to go, what to do, etc. v1 took me a day to do, so I wouldn't call this the most difficult Sonic game to TAS ever (and in no way wanted to convey that at all) it's just the physics are very different and tricky to make work for me, as opposed to against me. I wanted to figure out how the game works, in order to determine what to do in each situation and be able to construct proven methods/techniques of what is fastest.
Green Grove Zone 1 v2 is roughly 20% complete, ~20 frames saved so far. This will break the 47 second barrier for sure, so shouldn't take that long.
