The object of ‘Tradewinds’ is to earn victory points by controlling valuable trade routes. As colonists develop the local infrastructure, many islands will experience an economic boom. Before that happens, dominate the exports of an island by investing there more heavily than others...but the value of those exports depends on the population demanding the products, and how well funded they are. Of course, not all would-be colonists are particularly loyal subjects: make sure to deposit enemy sympathizers and other undesirables where they can do little harm.
(rulebook overview)
Thanks to the fine folks at gabob.com, there is a single-player Flash version available. It's still a prototype (only 4-5 player rules are fully implemented), but is already quite challenging!