Actually I mean the original one. Instead of the sand surface for the boss rush, it would be better if it just like Optomon did but forthe different colour, like the prologue of the game

Arseniy was right in this case.

Sorry, I have no time at this moment. Maybe later

I found a way to switch code banks without using any space in fixed bank.

**For example, this is original game code. Highlighted in purple is the part which we replace and relocate to new bank:**$D325:A9 00 LDA #$00

$D327:9D 90 05 STA $0590,X @ $05A7 = #$00

$D32A:BD 90 05 LDA $0590,X @ $05A7 = #$00

$D32D:D0 0F BNE $D33E

$D32F:BD 00 05 LDA $0500,X @ $0517 = #$D7

$D332:29 7F AND #$7F

$D334:9D 40 07 STA $0740,X @ $0757 = #$00

$D337:A8 TAY$D338:B9 41 D4 LDA $D441,Y @ $D445 = #$00

$D33B:9D 00 05 STA $0500,X @ $0517 = #$D7

$D33E:60 RTS

**This is new code. Replaced part highlighted in green, it is switching to new bank #07:**$D325:A9 00 LDA #$00

$D327:9D 90 05 STA $0590,X @ $05A7 = #$00

$D32A:BD 90 05 LDA $0590,X @ $05A7 = #$00

$D32D:D0 0F BNE $D33E

$D32F:A9 7F LDA #$7F

$D331:48 PHA

$D332:A9 FF LDA #$FF

$D334:48 PHA

$D335:4C 24 D7 JMP $D724$D338:B9 41 D4 LDA $D441,Y @ $D498 = #$08

$D33B:9D 00 05 STA $0500,X @ $0517 = #$D7

$D33E:60 RTS

**Part of switching subroutine which we point by JMP $D724 in the code above:**$D720:A9 06 LDA #$06

$D722:D0 E3 BNE $D707

$D724:A9 07 LDA #$07

$D726:D0 DF BNE $D707

**This is code we write in the new bank. Part of original relocated code in purple. After it you can place any of your new code. Finally you should return to previous bank (#6 in this example), the backswitching code highlighted in green:**$8000:BD 00 05 LDA $0500,X @ $0506 = #$D2

$8003:29 7F AND #$7F

$8005:9D 40 07 STA $0740,X @ $0746 = #$00

$8008:A8 TAY.....................

[HERE YOU CAN PLACE ANY OF YOUR NEW CODE]

.....................

$8009:A9 D3 LDA #$D3

$800B:48 PHA

$800C:A9 37 LDA #$37

$800E:48 PHA

$800F:4C 20 D7 JMP $D720**Now explanation how we point the address where we want to be after switching. Subtract 1 from this address in hexadecimal, then split it into two bytes, first byte put in first LDA, second put in LDA below. For example, 8000 - 1 = 7FFF, the result is:**$D32F:A9 7F LDA #$7F

$D331:48 PHA

$D332:A9 FF LDA #$FF

$D334:48 PHA