* A-Levels Imperial College London sequence on edX

* Sedgewick & Wayne CS & DS/Algos books & accompanying Coursera courses (alternatively, IIT Bombay's C++ sequence)

* LAFF Linear Algebra sequence on edX

* Open-ended puzzle/system design games (SpaceChem, EXAPUNKS, Magnum Opus, TIS-100, Factorio, Shapez.io, Mindustry)