Circles

Circles
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By Dmk 2024

I played this game with paper and pencil against my classmates. You can start playing it quickly as the rules are simple. 

You can:      Cross one or more circles horizontally or vertically  You cannot:      Cross circles diagonally      Cross over a circle that has already been crossed  Click as drag to make your move. The computer will respond using the same rules.  Whoever crosses the last circle loses.

I wanted to write a program for this game since I was 14. I had just learned a bit of BASIC and successfully programmed Tic-Tac-Toe using a bunch of if-then-else logic. I wanted Circles to be next. It so happened that I did not finish the game and could only return to it later when I was already in college studying computer science. 

I did not own a computer, but the lab had IBM PS/2 with ROM BASIC, and I stayed for hours after school trying to make the game work. And eventually, it did work, somewhat.

I did not know about the MinMax algorithm and the only way I could write this game was by pattern matching and random moves in case no pattern was found. There are several “looser” patterns in this game that an experienced player can spot. For example, leaving your opponent with an odd number of isolated circles has an obvious advantage, since it will be a “him-you-him” situation resulting in your opponent crossing the last circle. There are more patterns like that: two-and-two circles, 2x4 block of circles, two isolated 2x2 triangles, one 3x3 triangle, and perhaps some more. Whoever makes the first move being left with such a pattern loses.

For the game you are about to play here, the computer will do no pattern matching, although you will surely see these patterns created against you! This time the computer will make perfect moves suggested by the MinMax algorithm. Winning will be hard, but WINNING IS POSSIBLE.

Source code and assets are available for download below. EXE files included.