Java app for regular phones (MIDP2)
Java MIDP V. 2.1 is a very extensible plataform that still works and we every year see more apps for that, for example Whatsapp works in a Nokia C3-00 or a lot of games for example of Gameloft.
Is it possible a java app for Todoist? Simple task add (with calendar) and complete functions I think that is more that any want in a cellphone not smartphone.
HTML5 it is posible but in some phones it is not possible see the HTML5 in action because the data compresion.