Sonic Adventure/Sonic
From SDA Knowledge Base
Sonic Adventure is a great game to speed run in a live race or otherwise. It is full of glitches[1], some of which are useful for sequence breaking. The risk vs reward nature of different skips makes it a great game to race as the route can change in real time depending on one's risk tolerance and standing.
This page will refer to all versions of Sonic Advenuture and Sonic Advenuture DX. Skips that only work in certain versions will be noted and work in all versions if not noted, and will be listed in order from most difficult to easiest when one section has multiple options to skip.
Spindash Jumping
Performing a jump after spindashing on a slope produces absurd height and distance.
Camera Locking
With the default camera option, L+R will lock the camera behind Sonic. This is useful in getting the camera to behave for many skips.
Sonic's Story
Emerald Coast
(DX only) At the start, there is a tiny island to the left. A spindash-jump-homing attack through the right spot in the invisible wall can get Sonic onto the geometry where the sand touches the water. You can also get behind the invisible wall easily near the wooden bridge, but this doesn't save any time.
On the first wooden bridge near the beginning, a spindash-jump takes you to just before the first loop.
Right after the checkpoint following the first boost ramp, before turning right and running up the wall, you can stand on top of the barrier to the left and spindash-jump left to the loops just before the whale. This jump is one of the trickier ones.
During the whale scene, lock the camera and spindash repeatedly.
You can spindash up the left face of the mountain with springs next to the lighthouse.
In the second section of the level, before the tube Sonic runs around, jump off to the shallow water to the left. The boost ramp is just ahead.
At the boost pads that take you up a straight track, go right to the beach and take the spring at the end. Look at all those jump panels you skipped.