PGDmC: Knight Fever

[Winwardo]

The game is practically ready for upload, I just need to get all the art finished and into the game. Here's the main menu and a pic of you ingame.





The gameplay is very simple, two buttons for attacking, three buttons for movement, goblins spawn progressively faster as time goes on, and anytime a goblin dies without you killing it (such as in a lava pit) you lose points. Will have the game up ASAP

EDIT: Also, it suffers from a crippling bug that closes the game due to accessing a bad part of memory. I can't replicate this bug, and even with a try except statement and other stuff, it still SIGSEGVs.

function grabCollisionArrayPixel(xz,yz:integer;xx,yy:integer) : byte;
begin
  if ((yz mod 512) = 0) then inc(yz);
  if ((xz mod 512) = 0) then inc(xz);
  if(yy < 1) then yy := 1;
  if(xx < 1) then xx := 1;
  try
    result := arrayCollisionPixels[yy,xx]^[ (512 * (yz mod 512)) + (xz mod 512) ];
  except
    raise exception.create('Bad memory access');
    writeln('SIGSEGV noted');
    result := 255;
  end;
end;

If anybody could help me with stopping this from crashing I would majorly appreciate it. It's certainly not xx and yy being out of bound, and the second value can range from 0 to 262144. By my calculations, (512 * (yz mod 512)) + (xz mod 512) should never be larget than 262143, even if yz and xz are both 511. So any ideas?