I'm approaching my Someplace Else port to Source very differently from how I approached my early work on the Anomalous Materials chapter of Black Mesa Source. There, I felt I had significant license to add rooms and change architecture styles.
Because Someplace Else is so combat-heavy, it feels strange to do that. Anything beyond higher resolution textures, new shaders, and more surface geometry requires justification, which means studying what Foster did and extrapolating what he would've done with more resources and higher memory limits.
In the history of level design archaeology, I think the most convincing piece of writing has been Channie on the laundry room in Favela from Modern Warfare 2.
I don't think I'll be able to achieve such certainty about something, but it'll be fun to think about.
The biggest change so far has been to scale the entire level to be 1.5x larger.
The crazy part is that you probably wouldn't have noticed, especially if you played the original, because you remember it being huge and spacious by the standard of Half-Life levels at the time, and this new scale seems huge and spacious by the standard of most interior-focused Half-Life 2 levels today. The level itself hasn't changed, but we've changed as players -- so ironically, the original level wouldn't feel authentic to us at all. (Or at least that's been my experience.)
There are a few things on my mind as I go through each room to re-texture everything and convert stuff to their Source equivalents:
1) Will Black Mesa Source's monsters / damage values be equivalent to the original? What changes in enemy and item placement will be required?
2) Halfway through the level, you push a button to change the world state throughout the entire level. In the original, some holographic walls disappear in response, but I don't think most players noticed something so subtle. I think I'm going to make the change much more drastic: more lights turning off, more consequences.
3) In the original Button Room, there were some alien slaves waiting for you, and then some alien grunts spawn when you push the button. As it is, the Button Room had 2 problems in my mind: a) pushing the button felt like it didn't really do anything, and b) it was a grand setpiece with essentially the same combat as the previous rooms.
A long time ago, I toyed with porting Someplace Else to Sven Co-Op and one of my experiments was to put a garg there instead... and it kind of worked. Or maybe I should put a tentacle there? Then the tentacle could also interact with the player later, when they're on the upper levels of the Button Room? Or, maybe the button will disable the forcefield keeping the tentacle out. This would all reinforce the idea that this place is falling apart because of you.
x) Points 2 and 3 are based on the idea that you need to trigger a substantial world state change to convince the player to backtrack meaningfully. Currently, I think, your guide directly tells you to walk back, which can easily be forgotten or ignored. Or is that the point?