ZX Spectrum

Use File → Find games… to search the Internet Archive's Spectrum library, File → Open for your own .tap, .tzx, .z80, .sna or .szx files, or just drag one onto the screen.

Link straight to a game: /spectrum/?u=<file-url>&m=48. Add &k=OPeZ for custom touch keys (rows separated by commas; e=Enter, c=Caps, s=Symbol, _=Space, -=gap). Files on another domain must send CORS headers.