I tried to start writing a blurb, but I thought of a bunch of things instead.
Trade is NOT a good idea unless we can find a way to thoroughly differentiate it from capitalism; since Lasercake is an environmentalist game, it cannot accept capitalism as an okay thing.
Alternatives?
Altruism - traders come to bring you what you ask for (as much as you want - leave it up to the player to not have them dump a mountain of gold all over your fortress or whatever - or maybe there are (large) limits), and you can, if you want, give away things that you have in abundance.
Colonialist NGOs - they bring you what you want if you agree to carry out specific projects that have major design flaws.
Old fashioned colonialism - you can trade with them and they give you good deals, but if you do it too much then they know you're rich and then they invade and take your stuff.
Federation - Like Altruism except that if you want the help, you have to join and pay taxes proportional to your total productivity.
With any kind of trade there's the problem that you don't see the environmental consequences of gathering the stuff you trade for. "Altruism" was initially my favorite of the above, but "Colonialist NGOs" is the only one where you see bad and annoying environmental things happen because you called for the delivery of special resources. (Well, in "Old fashioned colonialism" bad things happen, but you could trade and then defeat them and feel good about yourself, which is wrong.)
Being able to subvert the NGOs' projects into something actually useful could be a nice feature too. But I'm still not sure it's good for trade to exist at all.
- Eli (from the Colby address: I've just signed this one up for the Google Group too, which seems silly but also appropriate since both Eli-as-a-Colby-student and Eli-as-a-person are involved in this project)