Add the code to handle restricting the spider to lower and lower rows as the score goes up. This is the final bit of game logic necessary for the bugs in the game I think.

BuGS/game.s

@@ -161,10 +161,6 @@ drawTile entry
         
 jumpInst jmp >mushroom1
         nop
-		
-addPlayer entry
-; TODO - Write code to add a new life.
-		rtl
 
         
 setupScreen entry

BuGS/gameFlea.s

@@ -163,7 +163,7 @@ updateFlea_nextTile anop
         bne updateFlea_nextAction
         lda #TILE_MUSHROOM4
         sta tileType,x
-		cpx #SPIDER_TOP_ROW_OFFSET
+		cpx #SPIDER_STARTING_TOP_ROW_OFFSET
 		blt updateFlea_nextAction
         inc numInfieldMushrooms
         bra updateFlea_nextAction

BuGS/gameSegments.s

@@ -1693,7 +1693,7 @@ shootSegment_doneScore anop
 		lda #TILE_POISON_MUSHROOM4
 		bra shootSegment_dirtyTile
 shootSegment_noMushroom anop
-		cpy #SPIDER_TOP_ROW_OFFSET
+		cpy #SPIDER_STARTING_TOP_ROW_OFFSET
 		blt shootSegment_normalMushroom
 		inc numInfieldMushrooms
 shootSegment_normalMushroom anop

BuGS/gameSpider.s

@@ -26,8 +26,8 @@ SPIDER_STATE_RIGHT_DOWN         equ 9
 SPIDER_STATE_RIGHT_UP           equ 10
 
 
-SPIDER_LHS_TILE_OFFSET      equ SPIDER_TOP_ROW_OFFSET
+SPIDER_LHS_TILE_OFFSET      equ SPIDER_STARTING_TOP_ROW_OFFSET
-SPIDER_RHS_TILE_OFFSET      equ SPIDER_TOP_ROW_OFFSET+(GAME_NUM_TILES_WIDE-1)*SIZEOF_TILE_INFO
+SPIDER_RHS_TILE_OFFSET      equ SPIDER_STARTING_TOP_ROW_OFFSET+(GAME_NUM_TILES_WIDE-1)*SIZEOF_TILE_INFO
 
 ; The spider starts 2 pixel rows above the top row offset so it can slide in on the edge of
 ; the screen on a diagonal and hit the centre of the tiles with the middle of its body.
@@ -63,6 +63,8 @@ SPIDER_ADD_TIME		equ 120
 spiderInitGame entry
 		stz spiderAddTime
 		stz spiderState
+		lda #SPIDER_STARTING_TOP_ROW
+		sta spiderTopRow
 		lda #SPRITE_SPEED_SLOW
 		jmp setSpiderSpeed
 		
@@ -418,7 +420,7 @@ updateSpider_tilesUp anop
         beq updateSpider_tilesUpCont
         lda #TILE_EMPTY
         sta tileType,x
-		cpx #SPIDER_TOP_ROW_OFFSET
+		cpx #SPIDER_STARTING_TOP_ROW_OFFSET
 		blt updateSpider_tilesUpCont
 		dec numInfieldMushrooms
         
@@ -493,7 +495,7 @@ updateSpider_tilesDown anop
         beq updateSpider_tilesDownCont
         lda #TILE_EMPTY
         sta tileType,x
-		cpx #SPIDER_TOP_ROW_OFFSET
+		cpx #SPIDER_STARTING_TOP_ROW_OFFSET
 		blt updateSpider_tilesDownCont
 		dec numInfieldMushrooms
         
@@ -507,17 +509,10 @@ updateSpider_tilesDownCont anop
 updateSpider_downChangeDir anop
         lda spiderTargetRow
         sec
-; TODO - The actual top row of the spider changes as the score goes up.
+        sbc spiderTopRow
-; The top row of the spider based on the score is:
-;   0 to 119,000       - 10th row
-;   120,000 to 139,999 - 9th row
-;   140,000 to 159,999 - 8th row
-;   160,000 to ...	 - 7th row
-        sbc #SPIDER_TOP_ROW
         jsl randN
-        inc a
         clc
-        adc #SPIDER_TOP_ROW-1
+        adc spiderTopRow
         sta spiderTargetRow
         
         jsl rand0_to_65534
@@ -561,14 +556,42 @@ addSpider_checkSpeed anop
 		bne addSpider_fast
 		lda gameScore
 		cmp #5000
-		blt addSpider_doit
+		bge addSpider_fast
+		lda #SPRITE_SPEED_SLOW
+		bra addSpider_setSpeed
 addSpider_fast anop
 		lda #SPRITE_SPEED_FAST
+addSpider_setSpeed anop
 		cmp spiderSpeed
-		beq addSpider_doit
+		beq addSpider_setHeight
 		jsl setSpiderSpeed
 
-addSpider_doit anop
+addSpider_setHeight anop
+; The actual top row of the spider changes as the score goes up.
+; The top row of the spider based on the score is:
+;   0 to 119,000       - 10th row from bottom
+;   120,000 to 139,999 - 9th row from bottom
+;   140,000 to 159,999 - 8th row from bottom
+;   160,000 to ...	 - 7th row from bottom
+		lda scoreNum20000
+		cmp #6
+		blt addSpider_height10
+		beq addSpider_height9
+		cmp #7
+		beq addSpider_height8
+		lda #SPIDER_STARTING_TOP_ROW+3
+		bra addSpider_doneHeight
+addSpider_height10 anop
+		lda #SPIDER_STARTING_TOP_ROW
+		bra addSpider_doneHeight
+addSpider_height9 anop
+		lda #SPIDER_STARTING_TOP_ROW+1
+		bra addSpider_doneHeight
+addSpider_height8 anop
+		lda #SPIDER_STARTING_TOP_ROW+2
+addSpider_doneHeight anop
+		sta spiderTopRow
+
         lda spiderStartingShift
         sta spiderShiftInTile
         
@@ -578,12 +601,18 @@ addSpider_doit anop
         lda #SPIDER_SPRITE_REFRESH_COUNT
         sta spiderSpriteRefresh
         
-        lda #SPIDER_TOP_ROW-1
+        lda #SPIDER_STARTING_TOP_ROW-1
         sta spiderCurrentRow
         
-        lda #SPIDER_NUM_POSSIBLE_ROWS-1
+		lda #GAME_NUM_TILES_TALL-1
+		sec
+		sbc spiderTopRow
         jsl randN
-        adc #SPIDER_TOP_ROW+1
+; We intentionally set carry before adding here.  I want to add (spiderTopRow + 1) to the
+; random number we already got.  That way, the target row is (spiderTopRow + 1) to
+; (GAME_NUM_TILES_TALL - 1)
+		sec
+        adc spiderTopRow
         sta spiderTargetRow
         
         jsl rand0_to_65534
@@ -768,6 +797,7 @@ spiderScreenShift   dc i2'0'
 spiderShiftInTile   dc i2'0'
 spiderAddTime       dc i2'0'
 
+spiderTopRow		dc i2'SPIDER_STARTING_TOP_ROW'
 spiderCurrentRow    dc i2'0'
 spiderTargetRow     dc i2'0'
 

BuGS/global.macros

@@ -158,7 +158,7 @@ _incrementScore_noCarry&SYSCNT anop
         sec
         sbc #12000
         pha
-        jsl addPlayer
+        jsl scoreEvery12000
         pla
 _incrementScore_noExtraMan&SYSCNT anop
         sta scoreWithin12000

BuGS/globals.s

@@ -29,9 +29,9 @@ SEGMENT_SPEED_FAST      equ 0
 SEGMENT_SPEED_SLOW      equ 1
 
 ; A spider only travels in the bottom N rows.  This defines that number.
-SPIDER_NUM_POSSIBLE_ROWS    equ 10
+SPIDER_MAX_NUM_POSSIBLE_ROWS    equ 10
-SPIDER_TOP_ROW              equ GAME_NUM_TILES_TALL-SPIDER_NUM_POSSIBLE_ROWS
+SPIDER_STARTING_TOP_ROW         equ GAME_NUM_TILES_TALL-SPIDER_MAX_NUM_POSSIBLE_ROWS
-SPIDER_TOP_ROW_OFFSET       equ SPIDER_TOP_ROW*GAME_NUM_TILES_WIDE*SIZEOF_TILE_INFO
+SPIDER_STARTING_TOP_ROW_OFFSET  equ SPIDER_STARTING_TOP_ROW*GAME_NUM_TILES_WIDE*SIZEOF_TILE_INFO
 
 SCREEN_BYTES_PER_ROW    gequ 160
 
@@ -141,11 +141,23 @@ BORDER_COLOUR_REGISTER  gequ $e0c034
 STATE_REGISTER          gequ $e1c068
 VERTICAL_COUNTER        gequ $e0c02e
 
+
 gameRunning	dc i2'1'
-numSegments dc i2'0'
+
-gameLevel   dc i2'0'
+; The following data values hold the game state and when/if 2 player is supported,
-gameScore  	dc i4'0'
+; this information will need to be copied to a backup location when the player
-scoreNum20000	dc i2'0'
+; switches.
+numSegments 		dc i2'0'
+gameLevel   		dc i2'0'
+gameScore  			dc i4'0'
+scoreWithin12000	dc i2'0'
+scoreWithin20000	dc i2'0'
+scoreNum20000		dc i2'0'
+centipedeLevelNum	dc i2'0'
+colourLevelNum		dc i2'0'
+; numInfieldMushrooms
+; tileType
+
 
 backupStack dc i2'0'
 

BuGS/level.s

@@ -144,8 +144,6 @@ levelNext_fastNoWrap anop
 		rtl
 
 
-centipedeLevelNum	dc i2'0'
-colourLevelNum		dc i2'0'
 centipedeNum 		dc i2'0'
 nextLevelFrameCount dc i2'0'
 

BuGS/score.s

@@ -328,9 +328,11 @@ scoreAddTwentyThousand entry
 		jmp scoreAddToTile
 		
 		
-
+scoreEvery12000 entry
+; TODO - Write code to add a new life.
+		rtl
+		
+		
 highScore	dc i4'0'
-scoreWithin12000	dc i2'0'
-scoreWithin20000	dc i2'0'
 
         end