Mods that add content from one game to another are nothing new. The mod scene is full of mash-ups that make no sense, so watching Star Fox Adventures’ Crystal appear in Half-Life 2 may be thematically weird, but it’s on par with the course of the modding community. It’s the next piece of this story that pushes things into really surprising territory.
The Half-Life 2 Krystal mod has evolved Gagnar’s idea, and he’s clearly a big fan of the Star Fox universe. You had to be to bring Krystal into Half-Life 2, but Gagnetar did not stop there. Believe it or not, he actually got Crystal’s original voice actress, Estelle Ellis, involved in the project.
Yes, Estelle Ellis has recorded dialog lines for the mod. The lines are pretty much the same as Alyx would say in the original Half-Life 2, but mentions of father / daughter connections have been removed. I mean, you would have nothing left that would break continuity or immersion!
If you’re looking for more of an explanation as to why this exists, you will not get one. Gagnetar is simply a big fan of Star Fox and Krystal in particular, so that’s all the motivation he needed to add her to Half-Life 2. There’s definitely something to say to follow your dreams!