Kim was a student at Digipen, she along with the students that created Narbacular Drop were hired by Valve through one of Digipen's expos for the seniors' projects. Robin Walker from Valve, approached them with an invitation to Valve HQ to make a presentation. Gabe Newell himself attended the presentation, after it was done, he pulled them aside to ask them if they wanted to work for Valve and recreate their game using the Source Engine.
The hiring of the whole Narbacular Drop team led to Portal, which was based on the core mechanics of their student project.
In early December of 2009, she left Valve to work for Airtight Games to take the lead on Quantum Conundrum. Jim Deal, the president of Airtight Games, said of Swift's move:
“[It] represents a strategic move by Airtight Games into new and broader gaming markets.” "[Kim will] build and lead a team in the development of games aimed at a more diverse audience."