https://clara.imslp.org/

The ultimate goal of the IMSLP is to gather all public domain music scores, in addition to the music scores of all contemporary composers (or their estates) who wish to release them to the public free of charge

IMSLP currently has 231,406 works, 755,950 scores, 83,070 recordings, 27,907 composers, and 2,027 performers.

Slipways is a great turn-based scifi empire builder that focuses on colonizing planets and building trade routes (titular slipways) between them to synergize. It has chill soundtrack, pretty visuals, and no war to stress about, your only worry is optimizing your empire layout