Hmm… one of the track I used in this seems to have been [update: found it!]. I’d spotted a piano work by urmymuse on ccMixter maybe 2 or 3 weeks ago. Was inspired to create something from that. Managed to find a few other samples that have not been remixed before (at least, not when I downloaded them).

I used Audacity to change the BPM. Other than the bass, everything you hear were cut from the ccMixter samples.