It's hard to overstate the influence Tokimeki Memorial had on the dating sims and visual novels that followed. Konami's 1994 visual novel took the social simulation mechanics of games like Princess Maker and applied them to high school, with the protagonist as a student who has to balance brutal amounts of study and exercise with an overactive social life.
Notably, Tokimeki Memorial writer Koji Igarashi was assisted in making the high school dating experience more authentic by his then-girlfriend—another Konami employee who was working on Castlevania: Rondo of Blood. (Igarashi used the success of Tokimeki Memorial as a springboard to switch series, becoming an assistant director, writer, and programmer on Castlevania: Symphony of the Night.)
After being released on PC Engine in 1994, Tokimeki Memorial was ported to Windows 95 as well as consoles including the PlayStation, Sega Saturn, and Super Nintendo. It's the latter version that's finally been made available in English thanks to SNES patchers Translated.Games, who've spent the last year working on it.
Under the name Heartthrob Memorial: Under the Tree of Legends, they've released a patch you can pop alongside the game in an emulator like Snes9x, which will not only replace the text with English but also add a few things from the original PC Engine version the SNES port was missing—an animated intro as well as voiced confession scenes and ending song. They've even smoothed the rate at which the tiled background scrolls, bless 'em.
If you're still curious about Tokimeki Memorial and why it matters, last year game critic Tim Rogers made an excellent video about exactly that, and it's well worth your time—should your time happen to include almost six free hours. (The video's separated into episodes, and the 'let's play' episodes in the middle are skippable by design if you'd like to knock two-plus hours off that runtime.)