Well, here is some feedback on the bic and whatnot.
As mentioned before, I think the lack of resources in Africa in particular needs to be corrected. I could send you mine if you desire or just write out additions I have made.
On the subject of Africa, I do not think you should have a Portuguese colony as "Rio de Oro" in Africa because that was a Spanish territoy and Spain still lays claim to the territory of Western Sahara, where Rio de Oro is. I think if you give the Portuguese an outpost as Luanda (Angola) (originally Sao Paolo de Loanda), it would be more accurate as the Portuguese had influence over the tribes by 1491, as well as it representing one of the foundations of the Portuguese slave trade, albeit the trade in general. Or, the Portuguese could get a base at Sao Jorge de Mina on the Guinea coast. I am not too sure where it specifically is (modern Elmina - unsure of locale). More resources in Africa would encourage further colonization as the Guinea coast was dotted with forts and trading posts from all major colonial powers throughout the period of the scenario.
I agree with that post somewhere else on this thread regarding the lack of colonization efforts in Asia and the East Indies and Africa. The next bic should aim to correct this. One thing that I was thinking was to give some nations outposts in the area. For example, the Portuguese established a trading post in Goa on the west coast of India in 1498, so maybe if you wanted to add that in (I know, I know - the scenario starts in 1490...) as well as some other outposts for other powers in the general area, it might expedite colonization. By the early 1500s, the Portuguese controlled or held influence over large swathes of Africa (especially southern and eastern). But at the same time, we do not want to lose track of the colonization of the Americas...
OK, some things that I have altered on my own bic - unit strengths, specifically the defense of the French musketeer and the to 3 from 2 with the rationale being that early musketeers seem to have a higher value on the defensive or from fixed positions. I don't remember if I raised the stats of the Arquebusier b/c I wanted to maintain the Musketeer's "uniqueness" as a UU for France. Either way, it's a thought. Also, I increased the attack value by one for "Line Infantry" and the defense value by 1 for the Line Infantry's period couterpart whose name escapes me at the moment. (Sorry for some of the vagueness as I am not on the usual computer I play Civ on and therefore cannot refer to the game and have not played the game in a little while due to other real world activities.) I fooled around with ship movement values b/c I thought it takes too long to circumnavigate the globe (I have not yet tested my fixes though, so I do not know if it was a good idea). Also regarding ships, I agree with some other post in the thread that the later ships should have better attributes to make me want to upgrade to them. Furthermore, I have lowered the cost of producing colonists from 80 to 60 as I felt that colonizing the new world was taking a long time. This I need to test. Basically, as it turned out, I had explored most of the world with explorers and soldiers but had only 6 colonies total! Also I believe the high cost of the colonists might discourage European powers from building them - I was playing as France and noticed that the Russians ventured to build a colony in Ethiopia while the other European powers (except the Dutch) had at most 3 other colonies. I also fooled around with the date system b/c the way it was originally set up, earlier colonization was being sped through rather quickly (eg. 25 months per turn for first 50 turns or something like that). As I type this, however, I think it makes some sense as most of the powers truly began expanding in the 1600s and 1700s. I did not play as Spain or Portugal and they are the ones who expanded during the early period of colonization, so as long as they have several settlers immediately ready to sail, then that part would be settled. This just needs to be compatible with the other aspects I mentioned above regarding timing, etc, for it to work properly.
Also, just as a thought, maybe 1900 is too late for the game to "end." I have not made it that far by any means, but just a thought. Maybe more something along the lines of 1850 and I say this because you have in the game the "Holy Roman Empire" (HRE) By 1900, they were long gone. By 1850, HRE was still technically in existence even though Prussia and Austria were the dominant players within the so-called "empire." By 1873, the HRE was basically obsolete with the unification of Italy and Germany complete. Plus, ending in 1850 allows the Napoleanic era "Fusilier" to be the ending unit, so to say, of the game, and not go into the "Rifleman" era. Having it ending earlier also allows some level of avoidance of Italian and German colonization efforts in the late 1800s after unification (Italians in Africa, Germans in Africa, Asia and Pacific).
I'll probably have some other things to discuss, but I have spent a while already at this post getting various accurate (?) information and trying to organize my thoughts. Let me know what you think and we can collaborate on the next release.
Regards, Imperialist.