Minesweeper for the Timex/Sinclair 2068
In 2003, Alvin Albrecht wrote a Minesweeper for the TS2068 in C, built with z88dk. Porting the Windows game to a Z80 was the easy half. The half he cared about was getting the computer to play it well, and to play it honestly: every move reasoned from the numbers on the board, never from the mines hidden underneath.