When student Isaac Ong started spending hours writing Java program code during the year-end holidays, his parents grew concerned.
"They asked if I should spend my time revising instead," he said. After all, the Dunman High School student will be sitting his A-level examinations this year.
But the 17-year-old, who was working on a game called Terasology for open source organisation Moving Blocks, had it all planned.
He had finished the bulk of his school work by the end of November before taking part in Google Code-In, a global software-development competition for students aged between 13 and 17.
Last month, Issac became one of 34 grand-prize winners because of his contributions to Terasology. This is the first time a Singaporean has been awarded the grand prize since the competition began in 2010. He won a four-day trip to the United States to visit Google's campus and meet the tech giant's engineers.
Two other finalists were Emily Ong, 15, also from Dunman High School, and Daniel Lim, 17, from NUS High School of Mathematics and Science.
The annual contest - from Nov 29 to Jan 17 - aims to introduce teens to open source software development. More than 1,300 students from 62 countries took part.
The term "open source" means the original code for the software is made available online and is open to contributions.
The students were assigned mentors provided by 17 organisations.
Emily, who was with a non-profit organisation called Sugar Labs, said: "The mentors were very helpful and made me want to continue working with them."
The mentors shortlist finalists and winners based on the quantity and quality of work produced.
Isaac had taken part in the competition twice before, but did not win anything. "Since it's the last year I could take part, I thought I would really try to contribute as much as I can to the open source projects," he said.
Both Isaac and Emily have continued contributing to the organisations after the competition.
As for Isaac's parents, they plan to accompany him to the US in June. He said: "I guess I managed to prove myself to them through this competition."