Sonic the Hedgehog 2 (sonicretro/s2disasm)

Sonic_Jump takes off at $680 subpixels per frame (6.5 px/frame), $800 as Super Sonic, and $380 underwater, the same take-off as Sonic 1. s2disasm/jump-speed

About: Sonic the Hedgehog 2 Jump

Value: 1664 1/256 px/frame

As in Sonic 1 (s1disasm/jump-speed, s1disasm/jump-vector), the speed goes along the ground's normal.

Cited by: Jump, Sonic the Hedgehog, Sonic the Hedgehog 2

ObjectMoveAndFall adds $38 subpixels/frame to Sonic's downward speed each airborne frame, and underwater the air modes take $28 back, leaving $10. s2disasm/gravity

About: Sonic the Hedgehog 2 Gravity

Value: 56 1/256 px/frame²

Cited by: Gravity, Sonic the Hedgehog 2

With no jump button held, Sonic_JumpHeight cuts a rise faster than 4 px/frame to exactly -$400 (-$200 underwater), as in Sonic 1. s2disasm/release-cap

About: Sonic the Hedgehog 2 Variable jump height

Value: -1024 1/256 px/frame

Cited by: Sonic the Hedgehog, Sonic the Hedgehog 2, Variable jump height

Obj01_Init sets Sonic's top speed to $600, his acceleration to $C, and his deceleration to $80 subpixels, Sonic 1's values; speed shoes and Super Sonic swap in others. s2disasm/ground-speeds

About: Sonic the Hedgehog 2 Running

{
 "top": 1536,
 "accel": 12,
 "decel": 128,
 "superTop": 2560,
 "superAccel": 48,
 "superDecel": 256
}

Cited by: Running, Sonic the Hedgehog, Sonic the Hedgehog 2

Holding forward no longer pulls a faster Sonic down to the top speed on the ground; Sonic_MoveRight undoes the frame's acceleration and keeps the speed he had. s2disasm/forward-cap-kept

About: Sonic the Hedgehog 2 Running

Sonic_MoveLeft does the same the other way. In the air Sonic 2 still caps (s2disasm/air-accel).

Cited by: Running, Sonic the Hedgehog, Sonic the Hedgehog 2

In the air Sonic_ChgJumpDir adds twice the acceleration, $18, either way and still caps at the top speed even when Sonic was already faster, as Sonic 1 does. s2disasm/air-accel

About: Sonic the Hedgehog 2 Air control

Value: 24 1/256 px/frame²

Cited by: Air control, Sonic the Hedgehog 2

Sonic 2 keeps Sonic 1's air drag; Sonic_JumpPeakDecelerate is instruction for instruction Sonic 1's Sonic_AirDrag, taking X speed shifted right 5 bits while Y speed is from −$400 to −1. s2disasm/air-drag-same

About: Sonic the Hedgehog 2 Air control

{
 "shift": 5,
 "vyFrom": -1024,
 "vyTo": -1
}

The camera reset ahead of it (Obj01_Jump_ResetScr, S1 Sonic_RollJumpLock) matches too, and a roll jump still skips the d-pad but not the drag.

Cited by: Air control, Sonic the Hedgehog 2

Sonic 2 has no grace window after a ledge: only the grounded modes, Obj01_MdNormal and Obj01_MdRoll, call Sonic_Jump. s2disasm/no-coyote-time

About: Sonic the Hedgehog 2 Coyote time

Value: 0 frames

Cited by: Coyote time, Sonic the Hedgehog 2

The spin dash starts when a jump button is pressed while Sonic shows his ducking animation; Sonic_CheckSpindash runs before Sonic_Jump and skips the rest of the frame. s2disasm/spindash-start

About: Sonic the Hedgehog 2 Spin dash

Cited by: Sonic the Hedgehog, Sonic the Hedgehog 2, Spin dash

Each jump press while charging adds $200 to the spin dash counter, capped at $800, and each frame the counter loses 1/32 of itself. s2disasm/spindash-charge

About: Sonic the Hedgehog 2 Spin dash

{
 "rev": 512,
 "cap": 2048,
 "decayShift": 5
}

Cited by: Sonic the Hedgehog 2, Spin dash

Releasing Down sets Sonic's ground speed from the counter's high byte, $800 plus $80 a step, from 8 px/frame uncharged to 12 at full charge (Super Sonic $B00 to $F00). s2disasm/spindash-speeds

About: Sonic the Hedgehog 2 Spin dash

[
 2048,
 2176,
 2304,
 2432,
 2560,
 2688,
 2816,
 2944,
 3072
]

move.b reads the counter word's high byte, so a counter of $800 picks entry 8. A release right after the first press gives $800. Each press adds $200, two table steps, but the counter leaks 1/32 of itself every frame, so presses spaced out in time stay below $800 and the top speed of $C00 needs fast pressing.

Cited by: Sonic the Hedgehog 2, Spin dash

On a slope Sonic's ground speed gains the sine of the angle times $20 a frame while he runs and $50 while he rolls downhill (a quarter of that uphill), with nothing while he stands; the code matches Sonic 1's. s2disasm/slope-factors

About: Sonic the Hedgehog 2 Slope physics

{
 "walk": 32,
 "rollDown": 80,
 "rollUpShift": 2
}

Both skip near-flat angles (angle + $60 ≥ $C0). The rolling quarter applies whenever the push opposes the roll.

Cited by: Slope physics, Sonic the Hedgehog 2

On a wall or ceiling below $280 (2.5 px/frame) ground speed, Sonic_SlopeRepel zeroes the speed, drops Sonic off, and locks the d-pad for 30 frames, as in Sonic 1. s2disasm/slope-repel

About: Sonic the Hedgehog 2 Slope physics

{
 "minSpeed": 640,
 "lock": 30
}

Cited by: Sonic the Hedgehog 2

Rolling, Sonic slows by half his acceleration ($6) a frame, by $20 more against the d-pad, and his X speed is clamped to $1000 (16 px/frame). s2disasm/roll-speeds

About: Sonic the Hedgehog 2 Rolling

{
 "friction": 6,
 "brake": 32,
 "xCap": 4096
}

Sonic 1's roll uses the same numbers (s1disasm/roll-speed).

Cited by: Rolling, Sonic the Hedgehog 2

Sonic curls into a roll when Down is held without Left or Right and his ground speed is at least $80 either way, as in Sonic 1. s2disasm/roll-start

About: Sonic the Hedgehog 2 Rolling

Value: 128 1/256 px/frame

Cited by: Sonic the Hedgehog 2

A hit throws Sonic up at -$400 and away from the object at $200 (half both underwater), and the hurt routine's gravity is $30. s2disasm/hurt-knockback

About: Sonic the Hedgehog 2 Knockback

{
 "vy": -1024,
 "vx": 512,
 "gravity": 48,
 "waterVy": -512,
 "waterVx": 256
}

Sonic 1 uses the same speeds and the same $30 (gravity-8) hurt gravity (s1disasm/hurt-knockback).

Cited by: Knockback, Sonic the Hedgehog 2

A hit sets invulnerable_time to $78 (120) and landing sets it to 120 again; it counts down only in the control routine, so Sonic has 120 frames of blinking invulnerability after he lands. s2disasm/hurt-invulnerable

About: Sonic the Hedgehog 2 Invincibility frames

Value: 120 frames

Obj01_Hurt_Normal doesn't reach Sonic_Display, so the count holds at 120 through the knockback.

Cited by: Invincibility frames, Sonic the Hedgehog 2

Hit without a shield, Sonic drops his rings, at most 32 of them as bouncing rings, and the count goes to 0; with no rings he dies. s2disasm/hurt-rings

About: Sonic the Hedgehog 2 Rings as health

{
 "scatterMax": 32
}

Cited by: Rings as health, Sonic the Hedgehog 2

Sonic 2's one shield takes a hit in place of the rings; HurtCharacter skips the ring drop, clears the shield, and knocks Sonic back as usual. s2disasm/shield

About: Sonic the Hedgehog 2 Shields

Cited by: Shields, Sonic the Hedgehog 2

Against objects Sonic is a 16 px wide box whose half-height is his height radius minus 3: 32 px tall standing, 22 px curled up. s2disasm/hitbox

About: Sonic the Hedgehog 2 Hitbox

{
 "w": 16,
 "h": 32,
 "rollH": 22,
 "duckH": 20
}

With fixBugs off the ducking box (20 px) applies only on one mapping frame, $4D, as the disassembly's comment says. Sonic 1's box has the same shape (s1disasm/hitbox).

Cited by: Hitbox

In the No-Intro Sonic The Hedgehog 2 (World) (Rev B) ROM, Sonic's object (Obj01) is the code s2disasm builds with gameRevision = 2, item for item, apart from absolute addresses, RAM variables at other addresses, branch displacements, and offset table entries, and less one jump table entry the build has after Sonic_HurtStop; the collision routines it calls (AnglePos up to Obj79), CalcSine and CalcAngle with their tables, ObjectMoveAndFall, ObjectMove, and ReadJoypads are that build's bytes. The build as a whole is not this ROM byte for byte. s2disasm/rom-matches-revision-2

So the lines cited in this set, read with gameRevision = 2, are the code this ROM runs; the one entry the ROM lacks is a local copy of a jump (JmpTo_KillCharacter) that removeJmpTos puts in the build, and the ROM's Sonic_HurtStop jumps through Obj01's own jump table instead. Sonic's movement routines have no gameRevision conditional; the one in his object is in Sonic_CheckGoSuper (the HUD timer check), outside the movement, and the animation scripts' rev02even only pads them to an even address in revision 2. The disassembly so gives the same movement code for revisions 0 and 1, but no probe here ran those ROMs. The ROM's RAM variables from about $FFFFFF60 up sit elsewhere: Player_option at $FF7C (the build's $FF72), Player_mode at $FF7A ($FF70), Two_player_mode at $FFB8 ($FFD8). The probes use the ROM's addresses (probes/jump-physics/sonic-2-lib.lua).

A frame-by-frame model of Obj01_MdNormal_Checks, Obj01_MdNormal, Obj01_MdRoll, and the air modes, with Sonic_Animate's timing for the standing and blinking animations, matches Sonic the Hedgehog 2 itself, run in MAME with Sonic alone on a floor built of Emerald Hill Act 1's blocks, on every frame of the movement lab's flat-ground presets, eleven scripts of Sonic 2's own moves, and 100 random input scripts. s2disasm/movement-rule

About: Sonic the Hedgehog 2 Running

{
 "ground": {
  "accel": 12,
  "friction": 12,
  "decel": 128,
  "top": 1536,
  "flip": 128
 },
 "roll": {
  "start": 128,
  "friction": 6,
  "decel": 32,
  "flip": 128,
  "cap": 4096
 },
 "air": {
  "accel": 24,
  "top": 1536,
  "dragShift": 5,
  "dragFrom": -1024
 },
 "jump": {
  "speed": -1664,
  "releaseCap": -1024,
  "gravity": 56,
  "rollShift": 5
 }
}

Sonic 1's frame (s1disasm/movement-rule) with these changes, in code order. A standing frame first runs Obj01_MdNormal_Checks (idle-blink), which can skip the whole frame. Then Sonic_CheckSpindash: while charging, or ducking with a jump press, it ends the frame after the floor snap with no move (spindash-start, spindash-charge, spindash-release). Moving forward above the top speed keeps the speed (forward-cap-kept). A standing Sonic with ground speed 0 checks balance (balance), and otherwise looks up or ducks. Rolling, the air, and landing are Sonic 1's. The ground modes end in AnglePos (floor-sensors, walk-off), whose reach down depends on his X speed. Obj01_Control copies the angle buffers to next_tilt and tilt after the mode, and then runs Sonic_Animate. A, B, or C going down is a press, with another held or not.

Cited by: Sonic the Hedgehog, Sonic the Hedgehog 2

On stages built in Emerald Hill Act 1 from the act's full flat 16 × 16 block, solid on the collision path Sonic starts on, the movement lab's Sonic 2 model matches Sonic the Hedgehog 2 itself, run in MAME, on every frame of 100 random stages with random input scripts, three in four with floating blocks, and of the lab's stage presets, until a fall into a pit kills him at the bottom boundary or he nears the end of the built floor. s2disasm/stage-rule

About: Sonic the Hedgehog 2 Hitbox

{
 "stages": 100,
 "frames": 300
}

The stages are Sonic 1's (s1disasm/stage-rule), from the same generator and seed: every edge on one 16 px grid, tops from 64 px down to 64 px up, pits, and in three in four two to eight floating blocks. The game runs them in its layout's rows 6 and 7 (y 768 to 1023), Sonic's starting floor at row 928, with rows 4, 5, and 8 emptied over the built span.

Sonic dies once his Y position is more than 224 px below the camera's bottom boundary, checked by Sonic_LevelBound before each move, as in Sonic 1, but with fixBugs off Sonic 2 checks the boundary where it is (Camera_Max_Y_pos) and Sonic 1 the target it's moving to. In Emerald Hill Act 1, run in MAME, each of 18 falls into a pit killed him on the first frame after his center passed row 1024. s2disasm/bottom-boundary

About: Sonic the Hedgehog 2 Fall damage

Value: 224 px

screen_height is 224. Sonic 1 checks the boundary's target instead (s1disasm/bottom-boundary), which fixBugs restores here. Emerald Hill Act 1's bottom boundary is 800 ($320), so the line is row 1024.

With neither Left nor Right held and the sliding status clear, a standing Sonic's ground speed moves 12 ($C, his acceleration) toward 0 each frame and stops at 0, as in Sonic 1; while sliding, Sonic_Move goes straight to Obj01_Traction, with no d-pad and no friction. s2disasm/ground-friction

About: Sonic the Hedgehog 2 Running

Value: 12 1/256 px/frame²

d5 holds Sonic_acceleration (ground-speeds); Super Sonic uses $C here too, by the override above it.

Turning against his motion on flat ground, Sonic skids (the stopping animation, still facing his old direction of motion) when his ground speed before the turning step is at least $480 going right or $381 going left, as in Sonic 1: the angle check overwrites the low byte of the speed it then compares. s2disasm/skid-threshold

About: Sonic the Hedgehog 2 Running

{
 "right": 1152,
 "left": 897
}

After $80 comes off, cmpi.w #$400 sees the speed with its low byte zeroed (the angle, 0 on flat ground): ≥ $400 going right needs $480 before the step; ≤ −$400 going left needs −$301 after it, −$381 before. fixBugs uses d1 and makes both $400 (s1disasm/skid-threshold).

Sonic's level collision radii are 9 × 19 px standing and 7 × 14 curled, set by Obj01_Init, the jump, the roll, and the spin dash, and his wall sensors sit 10 px from his center: Sonic 1's sizes. s2disasm/collision-box

About: Sonic the Hedgehog 2 Hitbox

{
 "w": 19,
 "h": 39,
 "rollW": 15,
 "rollH": 29,
 "radius": {
  "w": 9,
  "h": 19,
  "rollW": 7,
  "rollH": 14,
  "push": 10
 }
}

w and h are the spans the floor sensors cover standing (2 × radius + 1), rollW and rollH curled. Curling moves his center 5 px down so his feet stay put; uncurling moves it back. Same as s1disasm/collision-box.

Sonic 2's level collision is 16 × 16 px blocks whose layout words carry solidity bits for two collision paths; Sonic starts on the first, testing bit $C for floors and $D for walls and ceilings. As in Sonic 1, each search looks in the sensor's block and at most one more. s2disasm/collision-blocks

About: Sonic the Hedgehog 2 Hitbox

top_solid_bit $C picks Primary_Collision (a block's collision index on the first path) and $E the second; a block counts only if its word has the routine's bit set, a nonzero block ID, and a nonzero collision index. The lab builds its stages with both first-path bits set ($3000), so every block is solid from every side, like Sonic 1's. Path-switching objects and the second path's $E/$F aren't on the lab's stages. A search's distances are Sonic 1's (s1disasm/collision-blocks); a block meets a sensor that writes its angle ($FF for the full block) to the sensor's buffer.

On flat ground and not on an object, after each ground move AnglePos sets both angle buffers to 3, then reads two floor sensors at his feet, X ± his width radius, each writing its buffer when it meets a block; the nearer distance counts, and a floor up to 14 px above his feet lifts him onto it. Standing on an object, it sets both buffers to 0 and reads no sensors; on a wall or a ceiling it turns the sensors to match (Sonic_WalkVertL, Sonic_WalkCeiling, Sonic_WalkVertR). s2disasm/floor-sensors

About: Sonic the Hedgehog 2 Hitbox

The right sensor writes Primary_Angle, the left Secondary_Angle. A distance of 0 does nothing, and one deeper than 14 px leaves him where he is. As in Sonic 1 (s1disasm/floor-sensors), the stage's floor is flat, so the angle stays 0 ($FF, odd, snaps it to the nearest quarter).

When both floor sensors are above the floor after a ground move, AnglePos moves Sonic down onto it if it's within his X speed's whole pixels plus 4, at most 14; any farther and he's in the air. Sonic 1 reaches down 14 px at every speed. s2disasm/walk-off

About: Sonic the Hedgehog 2 Coyote time

{
 "plus": 4,
 "max": 14
}

mvabs.b x_vel(a0) takes the high byte of the X speed, its whole pixels rounded down, then its absolute value: below 1 px/frame (or −1 to 0 going left, whose high byte is −1, so 1) the reach is 4 or 5 px. So a slow landing that leaves a gap (a roll jump keeps his standing radius, roll-jump-size) lifts him off again. Leaving the ground sets the in-air flag and prev_anim, and leaves the speeds as they were.

On the ground, the wall check looks from where this frame's X speed will put him, 10 px ahead of his center and 8 px below it on flat ground, as in Sonic 1 (whose 10 px is sonic_quick_size). s2disasm/wall-sensors

About: Sonic the Hedgehog 2 Hitbox

Value: 8 px

CalcRoomInFront writes the direction it looks ($40 or $C0 on flat ground) to both angle buffers before searching; AnglePos sets them again later in the frame.

On the ground with nonzero ground speed, a wall found ahead (the sensor of wall-sensors inside a block) cuts this frame's X speed so he stops beside it, and sets his ground speed to 0, as in Sonic 1. s2disasm/ground-wall

About: Sonic the Hedgehog 2 Hitbox

Rolling reaches the same check from Sonic_SetRollSpeeds. The check is skipped upside down; with fixBugs S3K's flat-angle exception would apply, which doesn't change flat ground.

In the air Sonic_DoLevelCollision picks one of four checks by the direction of his speed: CalcAngle of X and Y speed less $20, to a quarter, as in Sonic 1, with the same angle table. s2disasm/air-quadrant

About: Sonic the Hedgehog 2 Hitbox

Value: 250 256 × |the minor speed| / |the major one| at the `$20` boundary

Mostly down: both walls, then the floor. Mostly left or right: that wall; if none, the ceiling; if none and he's falling, the floor. Mostly up: both walls, then the ceiling. The ratio at which the table reaches $20 is s1disasm/air-quadrant's 250.

In the air, a wall sensor 10 px from his center inside a block pushes Sonic out by whole pixels and sets his X speed to 0; moving mostly sideways, that ends the frame's checks, as in Sonic 1. s2disasm/air-wall

About: Sonic the Hedgehog 2 Hitbox

Both wall searches write Primary_Angle. Moving sideways into a wall copies his Y speed to his ground speed.

Falling mostly down, Sonic lands only if one floor sensor is no deeper in the floor than his Y speed's whole pixels plus 8, as in Sonic 1; moving mostly sideways he lands at any depth while not rising, with fixBugs off. s2disasm/landing-depth

About: Sonic the Hedgehog 2 Hitbox

Value: 8 px

The comparison is on bytes, against the Y speed after this frame's gravity.

Moving mostly up, a head sensor inside a block moves Sonic down out of it and sets his Y speed to 0 on a flat ceiling; moving mostly sideways it moves him down and stops a rise, and skips the floor check that frame, as in Sonic 1. s2disasm/air-ceiling

About: Sonic the Hedgehog 2 Hitbox

A steep ceiling (angle bit $40 after $20 added) would land him on it; the lab's full block reads flat.

On the ground nothing checks above Sonic except a jump press; standing or rolling into a block's underside leaves him inside it, as in Sonic 1. s2disasm/ground-no-ceiling

About: Sonic the Hedgehog 2 Hitbox

The wall check ahead looks 8 px below his center (wall-sensors), so a block whose underside is above that isn't a wall to him.

A jump press jumps only if both head sensors find 6 px or more of room above his head, as in Sonic 1; the check writes $80 to both angle buffers first. s2disasm/jump-headroom

About: Sonic the Hedgehog 2 Jump

Value: 6 px

The head sensors sit at X ± his width radius, his height radius above his center. The nearer counts. A failed check leaves the frame to run on, and its AnglePos sets the buffers again.

Standing on flat ground, not on an object, not sliding, and with d-pad control (move_lock 0), with ground speed 0 after the left and right steps and the floor under his center 12 px or more below his feet, Sonic balances on the side whose floor sensor met no block last frame (the right first). He turns to face that side only when he faces away from it and the floor 6 px back from his center is also 12 px or more below; Sonic 1 turns him at any such edge. s2disasm/balance

About: Sonic the Hedgehog 2 Hitbox

{
 "far": 12,
 "back": 6
}

next_tilt and tilt are the angle buffers as last frame left them (floor-sensors). Facing the edge he plays Balance, or Balance2 when the floor 6 px back is also gone; facing away, Balance3, or Balance4 and a turn. Balancing skips looking up and ducking, so Down at an edge doesn't duck and can't start a spin dash. As Super Sonic he faces the edge whichever way he faced (SuperSonic_Balance2).

A jump adds nothing to Sonic's X speed on flat ground, and the rest of that frame's mode (the move and the floor snap) doesn't run, as in Sonic 1. s2disasm/takeoff-x

About: Sonic the Hedgehog 2 Jump

addq.l #4,sp drops the return into the mode, so Obj01_MdNormal or Obj01_MdRoll ends there.

A jump from a roll sets the roll-jump flag, and while it's set Sonic_ChgJumpDir skips the d-pad, as in Sonic 1; the drag near the top of the jump still applies. s2disasm/roll-jump-lock

About: Sonic the Hedgehog 2 Air control

With fixBugs off, a jump sets the standing collision radii before checking for a roll, so a roll jump keeps them while curled, and lands 5 px early; landing then lifts his center 5 px more, as in Sonic 1. s2disasm/roll-jump-size

About: Sonic the Hedgehog 2 Jump

Value: 5 px

Landed with a slow X speed, the gap he lands with can be more than AnglePos reaches down (walk-off), and the next frame lifts him off again.

Landing on flat ground sets his ground speed to his X speed and his Y speed to 0, and clears the jump, roll-jump, and in-air flags, as in Sonic 1; out of pinball mode it also uncurls him (the standing radii, his center 5 px up), as Sonic 1 always does. s2disasm/landing

About: Sonic the Hedgehog 2 Jump

Letting go of Down while charging curls Sonic (Y + 5), sets his ground speed from the counter's high byte (spindash-speeds, or SpindashSpeedsSuper as Super Sonic), negated facing left, and ends the frame after the floor snap with his X speed unchanged, so he starts moving the next frame. s2disasm/spindash-release

About: Sonic the Hedgehog 2 Spin dash

Every spin dash frame (the start, each charging frame, the release) runs Sonic_LevelBound and AnglePos and nothing else of the mode.

Cited by: Sonic the Hedgehog 2

After Sonic has stood in his waiting animation to its 30th frame (about 175 frames), each frame with nothing held skips his movement, and the first frame with the d-pad or a jump button held but no jump press only starts a blink, which skips two more frames; from its 172nd frame he gets up instead, which skips five frames in all. s2disasm/idle-blink

About: Sonic the Hedgehog 2 Input reading

{
 "from": 30,
 "getUpFrom": 172,
 "wait": {
  "dur": 5,
  "n": 179,
  "back": 6
 },
 "blink": {
  "dur": 1,
  "n": 1,
  "to": 0
 },
 "getUp": {
  "dur": 3,
  "n": 1,
  "to": 0
 }
}

Obj01_MdNormal_Skip is the mode's rts with fixBugs off, so a skipped frame has no move and no floor snap. Sonic_Move sets the waiting animation whenever he stands with ground speed 0 and doesn't balance, look up, or duck; it restarts when the animation changes. The blink's script is one sprite entry shown for 2 frames (duration 1), from the frame that sets it, then $FD,0, which on the third frame switches to walking; getting up shows its entry for 4 frames (duration 3), so it runs five. A frame with nothing held changes nothing on flat ground but the animation. A jump press skips the check. rev02even pads each script to an even address in revision 2 and changes none of its bytes.

Sonic 2's movement on flat ground is Sonic 1's with five changes: the spin dash, a ground speed above the top kept while forward is held, a blink after standing that skips up to five frames of input, balancing that turns him only when he's far over the edge, and a floor snap that reaches down his X speed's whole pixels plus 4 rather than 14 px. s2disasm/movement-differs-from-sonic-the-hedgehog

About: Sonic the Hedgehog 2 Running

The changes, with the claims that hold them: spindash-start, spindash-charge, spindash-speeds, spindash-release; forward-cap-kept; idle-blink; balance; walk-off. Unchanged (each claim says "as in Sonic 1"): speeds, friction, the skid, rolling, the jump and its release cap, gravity, air control and drag, the four air checks, landing depth, the roll jump's lock and size, the headroom check, and the wall check ahead.

Cited by: Sonic the Hedgehog, Sonic the Hedgehog 2