A Portal-like game without using Portal assets and Valve had no leg to stand on…
This wasn’t taken down because it was based on Portal. It has nothing to do with Portal or Valve, really. It was taken down becuase it uses the official N64 SDK, which is still for some reason considered “confidential.” Valve said to take it down either under duress from Nintendo, or because Valve expected to be under duress from Nintendo and didn’t want to be. If it had used the libdragon API library instead of Nintendo’s official one, then this wouldn’t have happened and Nintendo would have been told to bite rocks.