OpenGameArt.org
Elegy for the Summer of 4096
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"Elegy for the Summer of 4096" by Aureolus_Omicron licensed CC-BY 4.0: https://opengameart.org/content/elegy-for-the-summer-of-4096
Where to put it: Game credits or video description. If the entry has a "Copyright/Attribution Notice", follow that.