Prevent double lock.

src/field.asm

@@ -1348,6 +1348,13 @@ FieldProcess::
     ldh a, [hDownState]
     cp a, 0
     jr z, .dontforcelock
+    ldh a, [hCurrentGravityPerTick]
+    cp a, 20
+    jr nz, .forcelock
+    ldh a, [hDownState]
+    cp a, 1
+    jr nz, .dontforcelock
+
 
     ; Set the lock delay to 0 and save it.
 .forcelock
@@ -1396,16 +1403,20 @@ FieldProcess::
     ; If the piece is locked, skip the ghost piece.
     ldh a, [hCurrentLockDelayRemaining]
     cp a, 0
-    jr z, :+
+    jr z, .postghost
 
     ; If the gravity is <= 1G, draw a ghost piece.
     ldh a, [hWantedG]
     cp a, 1
-    jr nz, :+
+    jr nz, .postghost
+    ld a, [wInitialA]
+    cp a, $11
+    jr z, .ghost
     ldh a, [hEvenFrame]
     cp a, 1
     jr nz, :+
 
+.ghost
     ldh a, [hYPosAtStartOfFrame]
     ld b, a
     ldh a, [hActualG]
@@ -1425,7 +1436,8 @@ FieldProcess::
     call DrawPiece
 
     ; If the lock delay is at the highest value, draw the piece normally.
-:   ldh a, [hCurrentPiece]
+.postghost
+    ldh a, [hCurrentPiece]
     ld b, TILE_PIECE_0
     add a, b
     ldh [hWantedTile], a

src/gbc.asm

@@ -64,7 +64,7 @@ ToATTR::
     ldh [rHDMA3], a
     ld a, LOW($9800)
     ldh [rHDMA4], a
-    ld a, 39
+    ld a, 40
     ldh [rHDMA5], a
     ld a, 0
     ldh [rVBK], a
@@ -83,7 +83,7 @@ ToVRAM::
     ldh [rHDMA3], a
     ld a, LOW($9800)
     ldh [rHDMA4], a
-    ld a, 39
+    ld a, 40
     ldh [rHDMA5], a
 
 
@@ -734,9 +734,38 @@ GBCGameplayProcess::
     cp a, $11
     ret nz
 
+    ; 20G?
+    ldh a, [hCurrentGravityPerTick]
+    cp a, 20
+    jr nz, :+
+
+    ld a, $00
+    ld d, a
+    ld hl, wShadowTileAttrs
+    ld bc, 32-12
+
+    ld a, 21
+    ld [wOuterReps], a
+.outer0
+    ld a, 12
+    ld [wInnerReps], a
+.inner0
+    ld [hl], d
+    inc hl
+    ld a, [wInnerReps]
+    dec a
+    ld [wInnerReps], a
+    jr nz, .inner0
+
+    add hl, bc
+    ld a, [wOuterReps]
+    dec a
+    ld [wOuterReps], a
+    jr nz, .outer0
+
 
     ; What to copy
-    ld de, wField + 40
+:   ld de, wField + 40
     ; Where to put it
     ld hl, wShadowTilemap + 1
     ; How much to increment hl after each row

src/res/tiles.inc

@@ -530,8 +530,8 @@ Tiles::
     DB $4A,$4A,$4A,$4A,$E4,$E4,$00,$00
     DB $CA,$CA,$2A,$2A,$2A,$2A,$4E,$4E
     DB $82,$82,$82,$82,$E2,$E2,$00,$00
-    DB $04,$04,$0A,$0A,$0A,$0A,$0E,$0E
-    DB $0A,$0A,$0A,$0A,$0A,$0A,$00,$00
+    DB $0C,$0C,$0A,$0A,$0A,$0A,$0C,$0C
+    DB $0A,$0A,$0A,$0A,$0C,$0C,$00,$00
 TilesEnd::