I've officially been poking around in this game's files for too long but I have finally found not only how to get it in fullscreen but also how to get the second achievement that seems to be broken. 

They're all separate games but on a technical level the files are interchangeable. So... that's what I did. 

Eu acredito que você clicou aqui neste guia porque estava preso na segunda fase do ICE TEMPLE ou nas fases do WIND TEMPLE porque o fireboy e a watergirl está andando ou pulando muito lento em comparação com o tempo e o cenário e os objetos. (pelo menos foi 

The original series has 6 games, out of which only 2 are released on Steam. So, I made some scripts to get other unreleased versions, officially available only for Android and as online game. 

Guía original de Starlight Skull. Todos sus créditos respectivos. Yo solo la traduje al español y simplifiqué el proceso, así que si quieren hacer el proceso paso a paso, véanlo en su guía.