Browsing this thread it would be easy to get the idea that
building the Great Lighthouse is going to be like
THE deciding factor in this game.
Poppycock!
GLH immediately gets +2 trade routes in one city. However, while you have no cities and no contact with AI, that is worth exactly nothing. Before you contact AI, after you've founded a couple more coastal cities, it is worth +2 commerce per city (which you can get with a cottage). Actually, until you know some AI with big cities and have trade routes open with those cities -- it isn't worth more than that.
You've started the game by cutting down all your trees and whipping your people to unhappiness and delayed expansion considerably. For some substantial returns much much later, yes, but what about now? This is Immortal level, recall. Do you really want to make it an OCC game?
Personally, I think you are probably just as well off not even trying to build the darn thing and just REX. Finding a good city site before the AI do is worth a lot more than a GLH, imo, even on a water map like this one. Now... if you ARE a wonder addict and insist on building at least one wonder this game, then by all means the GLH would be one of the most attractive... if you didn't have to build it in first city. However, when weighing against what you likely miss out on by straining for the GLH, I'd rather have some good cities.
It is not "game over" if you fail to build the GLH. But if you
try to build it and fail, that is a serious handicap which you may have trouble overcoming. And whether you get it depends if your opponent(s) are industrious leaders starting with fishing or mining -- fortunately for you there are none who are industrious who start with both fishing/mining, but plenty of non-industrious with that double combo. A test game won't get your opponents right for this competition... so by trying to pound out the GLH right off the bat, you leave a lot to luck. (Yeah... like none of them have stone lying around either... right... do you feel lucky, punk?)
Far better, imo, to ignore the GLH until someone else builds it. And then go capture it.