Kotonoha Days ! (0verflow's 2006 April Fools Joke)
http://youtube.com/watch?v=FQ3kRMx99DU (WARNING - Possible spoilers to SD game endings)
Neechin.net mirrored it, plus it has a better translation -
http://www.neechin.net/kotonohadays/sd_index.html
Wow, you only need a 386 with 128KB of RAM to play it...