In the running game, on flat ground, Sonic's top running speed, son_maxspeed, is $600 (6 px/frame): holding the d-pad his ground speed stops there, and in the air the d-pad caps his X speed there too. | Constants | Verified |
In the running game, on flat ground, holding the d-pad the way Sonic runs, or from a standstill, adds son_acceleration, $C, to his ground speed each frame, up to the top speed. | Constants | Verified |
In the running game, on flat ground, holding forward above the top speed pulls Sonic's speed down to it in one frame, on the ground and in the air, because Sonic_MoveRight and the air steering cap after adding without first checking whether he is already faster. | Top Speed | Verified |
In the running game, on flat ground, with neither Left nor Right held, Sonic's ground speed loses the acceleration, $C, each frame toward zero, stopping at exactly 0. | Constants | Verified |
In the running game, on flat ground, holding the d-pad against Sonic's motion subtracts son_deceleration, $80, a frame, and a step that would cross zero sets the speed to $80 the other way: from $40 written in by the probe, Left gives −$80, and from −$40, Right gives $80. | Deceleration | Verified |
A frame-by-frame model of Sonic_MdNormal, Sonic_MdRoll, and Sonic_MdJump2 on flat ground matches Sonic the Hedgehog itself, run in MAME on a floor built of Green Hill Act 1's blocks, on every frame of the movement lab's flat-ground presets and stress scripts and of 100 random input scripts. | Notes | Verified |