Portal RTX will be updated in December; it'll be a totally free DLC that adds ray tracing to Valve's puzzle game, initially launched in 2007 btw.

Portal with RTX DLC will be available on Steam on December 8th. After that, anyone who has Portal on the game platform will be able to download the dlc for free. The RTX version will have path tracing support for realistic lighting and reflections and improved textures and models with greater quality. Nvidia previously released an RTX version of Quake II.

All ray-tracing graphics cards are supported by the updated game. For playable framerates with DLSS 2, Nvidia recommends its own RTX 30-series, actually the RTX 3080, whereas 40-series users benefit from DLSS 3(opens in new tab) and its Frame Generation technology. It is unclear how the game performs on AMD or Intel GPUs, but the absence of RTX 20-series GPUs means the processing and performance cost will be considerable. 

Portal RTX DLC with ray tracing and DLSS to be released in December (for Free)