Short answers, pulled from the story.
Konami released the first Tokimeki Memorial game in 1994 across PC Engine, PlayStation, Sega Saturn, Super Famicom, Windows, Game Boy Color, mobile phones, PlayStation Portable, and Nintendo Switch platforms.
Hideo Kojima developed the drama series including Nijiiro no Seishun, Irodori no Love Song, and Tabidachi no Uta for PlayStation and Sega Saturn. Akari Uchida directed or produced multiple titles within the Tokimeki Memorial franchise over several decades.
The franchise earned the nickname TokiMemo among its fanbase due to the contraction of its full title. Characters from the series appear in crossover games including 2006 mobile phone title Konami Wai Wai Sokoban featuring Shiori Fujisaki.
Another manga tied to a specific game appeared on the 1st of July 2006, published by B's-LOG COMIC. Digital comics adapted from Tokimeki Memorial Online arrived in February 2008 for digital mobiles in Japan only.
One playthrough spans five to ten hours of gameplay before the final confession arrives. The goal is not to build character for its own sake but to become more seductive by graduation.