Considering that OpenTTD is a remake and expansion of "Transport Tycoon Deluxe" which was released in 1995, which itself was an expanded and improved version of

Considering that OpenTTD is a remake and expansion of "Transport Tycoon Deluxe" which was released in 1995, which itself was an expanded and improved version of "Transport Tycoon" which was released in 1993. That's a 28-year lineage now. Few games still receive updates like that...and maybe OpenCiv which was remake of the 1996 Civ 2 which was a new version of the 1991 Civ. Maybe NetHack which was started in 1987 and a fork of the 1982 game Hack has the record for longevity of continuously-updated game.