Thank you all for your helpful input. A few random responses:
It would be great to be able to play Homeworlds with an IceTowers set. *Lightly pound fist on table for emphasis* It has no orange, but it does have White.
Sorry Ryan, that's not a priority for me. We didn't sell very many IceTowers sets, and we don't plan to republish it. If that's the only set you've got and you want to play Homeworlds, you'll just have to map White to Orange. I'd MUCH rather play Homeworlds with 4 transparent colors than with 3 + White.
If the ultimate decision is to use a global color bijection instead of suggesting color designation for each game separately...
This was never the question. Although this may end up becoming a de facto standard color mapping, it will appear in the Homeworlds section and is intended for use specifically with that game. The lookup chart will include the function names as well as the colors names (despite what 3HOUSE proofreaders may expect, since this isn't true in the draft they reviewed).
Find 10-20+ random people, preferable people not familiar with Icehouse at all, or at least not homeworlds players.
I disagree with this approach. I'm more interested in a color mapping that feels right to Homeworlds players than one which random strangers think makes sense. However...
Go back to the beginning. It's not what color is what, but what action is what. So, with your four colors, I might suggest: Cyan - blue sky, movement from place to place. Orange - attack! Purple - a peaceful color for growing. Clear - Ice Traders! Change color.
... this is too radical. Cyan = Yellow? That's crazy. The colors need to feel like the best possible matches both for function AND for similarity to the standard colors.
Far from asking strangers for opinions, I'm most interested in what the Starship Captains on this list think. Therefore, the opinions of TwoShort and Zoltar carry the most weight for me. Unfortunately, they contradict!
I strongly prefer Andy's mapping. If I look at a Homeworlds position in Xeno colors and tell my brain to find the Yellow pieces (or Red or Green or Blue), it finds the right ones. I can put Cyan just as easily with blue or green. It's in between, both conceptually, and by my subjective judgment looking at the pieces. I can't see anything but orange making intuitive sense as red, nor purple making sense as anything but blue. Clear=Yellow is a bit arbitrary in the abstract, but looking at the pieces it works particularly well: yellow is by far the weakest and clearest.
This is exactly how I feel. To me, Cyan reads as blue-green, an aqua shade that's close enough to sea-green to feel greenish enough to me.
It seems to me that I get utterly confused if I don't map the Cyan to Blue, as I'm now wired to see any shade of blue as blue, and for trading colors. Given that, you can map the other three colors any way you'd like and it's about the same for me ( e.g. you could map Orange to either Red or Yellow) -- I guess it's down to the aesthetic or cool metaphor choices -- but if cyan doesn't map to blue I'm going to be confused and it's going to be hard to play
...whereas I think I'd be more confused by orange mapping to yellow. Like Rhymes-With-Cyan said, orange just feels more like red while yellow feels more like clear.
But perhaps James has the answer:
Blue=Cyan Obvious correlation Red=Orange Hottest colours Yellow=Clear Lightest colours Green=Purple Both are one step from blue
That's not bad, actually... the Green-Purple becomes the hard one to remember, but Jacob seemed to think they work logically, and they're both in the cool end of the spectrum... I think I could live with this choice, what do others think? (In particular, TwoShort and Zoltar?)
I would love to see yet another Treehouse color quintet released.
Actually, this is something we've been actively discussing lately... but that's an entirely different subject.