Chessboard
Board games have been known since ancient history, with the oldest records being paintings in mastabas of the First and Third Dynasties of Egypt (3100-2700 BC). The first known version of chess appeared around the 6th century in India and was called Chaturanga, played on a board of the game Ashtapada. This board was monochromatic and divided into eight columns by eight rows, with special marks called "castles" in the first, fourth, fifth, and eighth squares of the "a", "d", "e", and "h" columns, which served a function in Ashtapada, but not in Chaturanga.
Netrek
Developed as a successor to 1986's "Xtrek", "Netrek" was first played in 1988. It was the third Internet game, the first Internet team game, and as of 2011 is the oldest Internet game still actively played. It pioneered many technologies used in later games and has been cited as prior art in patent disputes. "Xtrek" and "Netrek" are the oldest games of what is now called the MOBA genre.