Short and semi-sweet.
The intro tune is good and the story is above half decent, but you might want to pick a different name for the little sister (some are already familiar with Sora being a guy's name, so maybe add "na" or something to the end to make it more fitting to be a girl's name?) and more importantly, the artwork sucks (teacher with two pupils? not to mention the eyes of the main characters often being white or missing). Minigames with Game Over conditions could also be a fun addition.
I saw a review say you should have multiple paths for the story, but I say keep it linear so you don't have to have multiple episode 3s or something like The Sagittarian where there were so many story arcs that an already dead character was mistakenly allowed to live (Shane in Episode 3, Gambling Fever). On the other hand, if you think you can handle it and know you'd want to do it all (it would likely take loads longer though), multiple story arcs could be fun too.