The characters are created from the original gameboy cover, Wario from the virtualboy gamecover, and the background are a mix edit/adapted from Wario land 2.

Thanks to Marc as this would not have been possible without the amazing tool he made.
Adrián B.R. (Pernom)
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Credits for the tool (Super Game Boy Border Injector) to Marc Max (@marc_robledo)

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Database match: Wario Land - Super Mario Land 3 (World)
Database: No-Intro: Game Boy/Color (v. 20210227-015730)
File/ROM SHA-1: AE65800302438E37A99E623A71D1C954D73C843E
File/ROM CRC32: 40BE3889