EpicWin is a playful productivity app, created by Rebox. It costs $2.99 US, and has to be the most effective to-do list on my iPod.
I first heard about it online, through Twitter, I think, as an effective to-do list that combines productivity with the fun and adventure of a role-playing game. Since I didn't have an iPod or iPad at the time, I put it on the list of things that would be cool, and forced myself to continue in conventional to-do lists.
When I did get my iPod, it was one of the first Apps I bought, and it has served me well. I have my own character, whom I level up by collecting experience points from completing tasks, or "quests", on my daily list. Not only that, but I also collect gold and loot, which gives me an immediate reward for my work. The instant gratification then encourages me to complete more "quests".
On really productive days, I've been able to complete two days worth of tasks, just because I have an easier way to keep track of what I need to do, and a fun way to cross them off my list. So I've found that part of the app to work.
I also found that EpicWin is easy to use as well, and since the developers keep updating it, continues to increase effectiveness, especially, I find, with adding and organizing new tasks.
Tasks/Quests are organized by when they're due, including Overdue and Whenever spots. When adding a new task, there are options on when it's due, to add an alarm, how much epic-ness the task is worth, and the type of feat it is: Strength, Stamina, Intellect, Social, and Spirit, which corresponds to your character's abilities and works towards the character's leveling-up.
What's also handy is the option to have tasks repeat, and if so, how often. I know that I have a list of daily repeating tasks to remind me to do things like shower, take meds, brush my teeth, and exercise, as well as tasks that repeat every few days, like wash dishes and vacuum. Combined with other one-time tasks, like calling specific people, or return library books, I've been able to become more productive than I was with paper and other app to-do lists that overwhelmed me.
Therefore, I highly recommend this app, maybe not even just for Autistic adults, but for Autistic children and youth who are developing independent skills, or want to be more organized and remember what they need to do. It combines a very easy to use interface with clear due dates, and fun instant-rewards.