@seangreen, just understand that because of coding errors, the scenario will not run even if it was not blocked. You could click the big green 'Open in Greenfoot' button (above and to the right) to download the source code in a jar file (suffix of ".gfar"), move it from your 'downloads' folder to your 'Greenfoot/scenarios' folder, open your greeenfoot program and load the file to open the project. Then open the editor for each of the subclasses of Actor (arrows going down and to the right from the Actor class), find where the image filenames are and change the first letter in each one to a lowercase letter. You will then be able to compile and run the project.

@seangreen, even if it was not blocked, it still would not run. Exceptions are thrown during world construction due to incorrect file name references in the code. You can download it and open it in your greenfoot application. Then go through the Animal subclasses and change the references to begin with lowercase letters. Then it will run within the greenfoot application.

It would be a lot easier to help if you made the source code available to look at. Please re-upload with the 'Publish source code' checkbox checked.

@DStasiak, I just updated my Global Defense game to allow users to view class codes without having to be logged in on the site. You may want to view the Missile class code in it.

@DStasiak, for the missile movement, there are a couple of ways to handle it. One is to track the coordinate locations using 'double' fields (greenfoot uses 'int' fields which is why only multiples of 45 are achieved when moving one pixel at a time). The other way is to have the missiles hold their starting location and count the steps it takes so you can increment the step, relocate back to the original location and move a greater distance each time.

@AreebRaza, in the 'getUnivX' and 'getUnivY' methods, the amounts returned do appear to be totally screwed up. I must of had a brain-fart the day I wrote them. Maybe I should just have a 'getScrolledX' and 'getScrolledY' methods and let the user determine what to do with the information they return (so the above could be ascertained with 'int x = getX()+getScrolledX();'). Those methods are not used within the SWorld class itself, so changing them wont hurt anything.

@AreebRaza, after reviewing, I find that all you need to do is change all occurrences of 'getWorld()' to '((SWorld)getWorld())'.

@AreebRaza, please start a discussion thread on this and use code tags to display the code (see below the 'Post a reply' box for the link 'Posting code? Read this!'). In the meantime I will look over my SWorld class to re-familiarize myself with it. Oh, and usually, lag will occur with larger backgrounds and/or too many objects in the world.

@kinder1, the source code is available for download. This will include all the images and sounds used within the project. Just click the big green 'Open in Greenfoot' just above and to the right of the scenario window to download the 'gfar' file which you can then open from within the greenfoot application (you may have to move it into your grenfoot/scenarios folder first). When you open it, a scenario folder will be created with a 'sounds' and 'images' folder included within it.