NonGNU ELPA - gnosis

Gnosis (γνῶσις) is a spaced repetition system that enhances memory
retention through active recall.  It employs a Q&A format, where each
note consists of a question, answer, and explanation.  Notes are
reviewed at optimally spaced intervals based on the user's success or
failure to recall the answer.  Key benefits arise from writing out
answers when reviewing notes, fostering deeper understanding
and improved memory retention.

Gnosis algorithm is highly adjustable, allowing users to set specific
values not just for note decks but for tags as well.  Gnosis'
adjustability allows users to fine-tune settings not only for entire
note collections but also for specific tagged topics, thereby creating
a personalized learning environment for each topic.