While at DigiPen, Swift led the team that created Narbacular Drop, a game that showcased innovative portal mechanics and caught the attention of Valve.

Valve Corporation hired the team behind Narbacular Drop, including Kim Swift, integrating them into the company's development structure.

Served as a key designer for Portal, which was released as part of The Orange Box. The game was a critical and commercial success, and she played a vital role in shaping its core mechanics and innovative puzzle design. She is credited as a designer on the original "Portal".

Contributed to the development of Left 4 Dead, a cooperative first-person shooter focused on zombie survival. Her work likely involved level design and gameplay mechanics.

Continued to work on various projects and prototypes within Valve, potentially experimenting with new game concepts and technologies. She possibly contributed to Portal 2 during this time, though it may have been in an early stage, or a less direct way, since she departed Valve before it was finalized.

Left Valve Corporation, marking the end of her tenure at the company. The reasons for her departure are likely related to seeking new challenges and opportunities.