I don't remember how I got the idea for this game. In this game you were supposed to be a cop and had to solve crimes and mysteries, drive around in a car or a motorcycle and shoot other people.
I thought it would be interesting if you saw the whole action from above, so that all the people were just a small circles moving around, buildings, trees, shrubbery, backyards, everything would just be seen from some sort of a birds eye view.
The game was supposed to have a eight way scrolling using regular CRTC register 12 and 13 scrolling commands. The strees, sidewalks, buildings, etc. were all composed of two by four bytes squares in order to provide maximum variabilty in combining the element to form any possible object.
I've created an editor with which you were able to compose buildings and other large objects. These objects could be placed anywhere on the map of the town. I thought I could safe a lot of memory by that approach. But then I had to realize that though the intention was good the practical conversion of that idea would be rather difficult, since i this way the map was composed of a number of unequal sized objects intermixed with regular block sized elements.
Creating a smooth and quick scrolling with this approach is virtually impossible, since the computer has to keep track on which part of what objects is going to enter the screen and what part of the two by four byte squares has to be clipped.
This problem was the main reason for abandoning this idea. What's left is a one screen test where you can move a small dot around a part of the city and the editor with which you can create blocks of houses, large buildings, parks, lakes, etc. save these objects to the disc and put them into a single screen map, wich can be also save to the disc.
One more thing about the single screen demo is of interest. I've used a special trick to find out where the player was allowed to go and where he wasn't. I used to have huge problems in other unfinished games to find out where the player could go and where he couldn't.
Therefore I came up with a good idea for this game to avoid these problems. I figured that the cop would be moving mainly on the street or the sidewalk. So when player presses any direction the computer tests whether the next set of background-bytes in this direction contains any of nine possible combinations of white, gray and black pixels in a byte (gray-gray, gray-white, white-gray, gray-black, black-gray, white-black, black-white, white-white or black-black - remember bytes in Mode 0 always contain two pixels).
If all of the bytes in the pressed directions were among these nine bytes the character was allowed to move into this direction. I just had to make sure that all the places where the cop wasn't allowed to go contained at least one pixel of a different color.
Controls for the game:
Use the cursor keys to move
Controls for the Editor:
L - to load something
H to load a pre-defined house (0 and 2 are still working)
S to load the screen
Cursor keys to move cursor, space to draw
Q/ A - circle through segments
0 - 9 - select type of segments
Copy - to draw