Hello everybody.
I don't know if homebrews also count, but I take this opportunity to mention the now forgotten VNDS interpreter, the famous Visual Novel Reader later ported to Android, with which you can read:
1) about the action/horror genre, masterpieces such as Fate Stay Night, Tsukihime, Saya no Uta;
2) as regards the mystery/suspense/ romantic genre, the wonderful Infinity Series (Ever17, Never7), Cross Channel;
3) for the dramatic/moving genre, Narcissu1/2, Kanon, Planetarian, etc;
4) for the erotic (H) genre, almost the entire Sono Hanabira series.
Personally I consider FSN an absolute masterpiece and I recommend it to all lovers of frantic action, multiple choices and twists (and with a lot of free time to read it); instead Narcissu1/2, with a more linear plot, is for more delicate and sensitive palates, sometimes exaggeratedly moving, but full of moral teachings.
Kanon has a romantic, touching and engaging plot, even though it is everyday life, and the characters, as for the other Key novels, are chubby, sweet and cute.
Instead I recommend staying away from the Hanabira series; I tried to read the first 2 episodes without finishing them (and they are also short), and personally I consider them terrible, with a banal, ridiculous and boring plot, characters that seem underage and with disgusting and unbearable H scenes (for anyone with at least an iota of sanity).
It would be nice to see other titles ported to DS, but while converting foreground /background images, sounds, voices is quite simple, converting script files is more complex and time-consuming and requires precise technical knowledge.
