Clannad (http://store.steampowered.com/app/324160/), one of the iconic visual novels from Key... over a decade old...
Just went on steam at 50$ price tag and leapt to top 3 in sales in the same day.
Wow. Finally a VN on steam worthy the title. Pricey, but there is ~80 hours of story to it, so figure from there. On sale as well at the moment.
In absolutely unrelated news, it's a good time to buy stocks in tissues.
https://www.youtube.com/watch?v=nYfldm73tWI
Only video could find that didn't spoil. Though if you insist on knowing the lyrics, have a translation (http://www.animelyrics.com/game/clannad/chiisanatenohira.htm)
*amusingly by the comments seems common to tear at hearing the opening notes :P
https://www.youtube.com/watch?v=7PkbqdAFIRU
(https://s-media-cache-ak0.pinimg.com/736x/60/0a/78/600a78e63b21d3eff68166defc5a4404.jpg)
「…パパ。ママのうた、うたって」