Block Five is a straightforward Gomoku (five in row) with no special frills. Personally, I prefer Turbo-Gomoku. It does have the added curiosity of being an early Apogee game. Apogee, of course, would later become better known for titles like Wolfenstein 3D or Rise of the Triad.
Block Five was published in the June 1989 issue of Big Blue Disk, a monthly disk magazine by Softdisk. It had, however, been submitted by Scott Miller far earlier, on 1988-01-20. Since he submitted it along with five other programs, it may well have been finished in late 1987. I mainly mention these details to show that giving exact dates, and thus creating an exact timeline, in connection with computer games is often difficult.
