I've made it about 2/3 through the time limit for my first game and am probably going to stop as I don't think I'll be built up enough to survive through independence. Outside of some basic similarities at the visual level due to using the Civ4 engine, gameplay is drastically different (it's been so long since I played the original I don't remember exactly how that game played).
I'll give some basics as how the game plays out. At start you can select to be a french, english, spanish, or dutch expedition. Each has 2 leaders with 2 special talents, effects are similar to Civ4 variations. For the map you can choose and island hoping experience with the Caribbean setting, or go fro mostly land with Americas. I chose Americas and English.
While the map doesn't use actual topography, since it spans from north to south pole it will have some similarities. I landed about where Texas would be, French in Florida, and Dutch in New York. South America was nothing but natives as well was the western part of the northern continent.
When you start you are at sea with a couple colonist loaded and no land in sight. First priority is to get the first settlement up. Since you must trade often with Europe, starting on the coast line is pretty much mandatory. Unlike Civ 4, here you only work the immediate 8 tiles around your town placement. Also you don't have a 2 hex dead zone around your town which no other town can be placed, you can go adjacent if you want to. While you may see a whole lot of resources in the tiles, you can only gather one resource per tile except for your town tile (I've seen as many as 14 resources per square and as little as 2 so placement of town again is vital.)
The main units of the game are colonist. You have standard colonist which you can select to do anything (although some like solider requires you to either make or buy guns). You also have specialist (they do double work, which allows double gathering as a field worker or double production as a manufacture [6 vice 3]). Most of your specialist will be brought from europe. I haven't done so myself, but you have certain school buildings you can buy that will allow you to train new specialist if you already have one in your colony. The indentured servant is a reduced colonist that will gather as normal but produces 1 less. A converted native (made by creating a missionary and establishing himself in a native settlement) is similar to indentured with a -1 production penalty, but they also get a +1 gather bonus. Other units you can make are foot or mounted soldiers, scouts (mounted explorer), pioneer (engineers), and previously mentioned missionary.
The goal of the game is to become independent from Europe. The longer you successfully run your settlements they will slowly grow in rebel sentiment. Once hi enough you can declare independence at which point your European sponsor will send troops to stop the revolt. You will receive periodic messages that due to growing rebel sentiment your sponsor has added troops to the army. I explored mostly the non military aspects of the game so can't say much more than this so far.
The depth of the game is in its exploration and resource management. At start each town can hold 100 of every resource, gathered or manufactured (excluding food). You can build warehouses with each one raising the limit by 100. At the beginning you get a fairly regular stream of European colonist and I tried to use them to establish my own colonist producing town (I had an expert fisherman and farmer giving my 2 tiles with double food production). This worked well till I hit a pop of about 6, but then non food gathering pop began bogging down growth here and food in general is scare enough to prevent much benefit from switching all your gatherers to just farm. My first town was on a 5 food/5 tobacco spot and I did get a cigar specialist rather soon, so cigar production did give me a fairly steady source of income early in the game. Next time if able to get an industry up soon I'll try and buy more people early on. Your ability to grow religion points directly affects how quick colonist want to come, so building churches should be emphasized by mid game. You can also build wagon trains which will allow you to either transport resources from one of your town to another, or to deliver them to a native settlement for trade. Speaking of industry, as I mentioned you can gather one resource from each of the 8 tiles around your towns (while specialist get a bonus in gathering or producing their certain specialty, you can still use them in other gathering/production areas at the basic colonist rate), but you produce by moving colonist to industry buildings which are already set for use at establishment of the town (a few such as arms manufacture do require the construction of the building first. A basic colonist makes 3 of an item (spec is double that), but you can build improved versions of the industry that gives a +# to production. Each industry slot can accept 2 colonist. There is also "industry" for hammer production, religion point production, and liberty bell production (a culture rating type).
As I said I haven't done much militarily (as a possible result I also have very good relations with the natives) but from the manual description great generals perform exactly per civ4. The other leaders you get are call founding fathers and do not show up on the map. You have a system of points, political, explorations, religion, trade, and military. The final four are gained in ways that are fairly obvious per their names. Political is a catch all that comes from liberty bells/rebel sentiment. The other four also increase with the same that make up political in addition to doing their named task. I don't recall the exact number, but each group of founding father class has like 8-12 selections. To get them the first colony to reach enough points (political is just politcal, the other 4 branches is political and the explorations, trade, religion, or military points as applicable) may select that founding father. Doing so gives you as colony wide bonus. Rejecting the inventation to join means that founder will never ask to join again.
I saw that it's on sale again at CC for $25. I think you'd be hard pressed to find a better new release at that price point if you are at all interested in this type of game.