There a source port of at least portal 1.

https://github.com/AruMoon/source-engine

Here’s the active fork of the original project. Going through the issues of the original project, it seems to have support for building for 64 bit platforms.

No portal 2 support though. Although mentioned in the issues of nileusr’s repo is this: https://github.com/EpicSentry/P2ASW , which is interesting

There are many, I think. Like what other people have mentioned, sometimes the new standard is just better on all metrics.

Another common example is when someone creates something as a passion project, rather than expecting it to get used widely. It’s especially frustrating for me when I see people denigrate projects like those, criticizing it for a lack of practicality…