The strategy game to which all others are compared.
PROS
There are so many things going for Conquest that it's difficult to know where to begin. Perhaps the best place to start would be to talk about the variety. That, in a nutshell, sums up the game. There are a variety of factions, each with basic similarities, yet enough variance between them to make them play differently. The English, for example, have an advantage in naval combat; the French, with artillery. If this sounds similar to something like Civilization, it is, a bit. However, it's done better here, as all the factions actually do play differently, instead of only some of them playing like that while others only have token differences.
Speaking of variety, you can alter the size of the maps, ranging from tiny ones to enormous ones. You can set practically any variable you want (hostility of native villages, number of native villages, number of resources, amount of water in the world, etc.) to almost any degree you want, except turns, which are capped at 300. The degree of customization here gives the game enormous replay value.
When exploring the map, anytime you discover a river/mountain/etc., you get to name it. The same goes for founding cities. In addition, there are also various "special" locations you can discover, which give you a bonus depending on what it is. For example, if you find the "Temple of War," your military units gain experience and a combast bonus. If you find the "Fountain of Youth," your cities grow faster. The kicker here is that, unlike in other strategy games with similar things, these locations don't disappear upon discovery. Rather, they stay on the map, and if you want their bonuses, you are forced to either garrison troops there to defend them, or build a city next to them for the same purpose. If you don't, any rival that stumbles upon them or sends troops there can claim them, and the bonus (or bonuses) will transfer to them. It adds another layer to the strategy aspect of the game, and lessens the luck quota. After all, if group A lucks out and has lots of special locations near them, just because group A found them first doesn't mean no one else will have a chance to get them.
The combat system in Conquest is unique to any strategy game I've ever played. Basically, when you take your troops into battle, you get an overhead view of the battlefield that is similar to a chess board. You deploy your troops, watch the enemy deploy theirs, and then take turns firing at each other (very similar to what European warfare of the time was actually like - which is to say, they all stood in lines and fired at each other). Depending on the size of your army, the type of your units, how much training you've given them (you can research your army by spending money at a building called a "War College"), and most importantly, the strategies you use, you can win big, or get your butt kicked. It's extremely fun, and it blows the combat system of something like Civilization Revolution out of the water where you merely send your units into battle and await a result. In Civ Rev, battles are mostly luck and numbers with a little bit of strategy; here, it's the reverse.
Maybe the funnest part of Conquest is the diplomacy system. You can trade with your rivals, declare war on them, ally with them, etc. If you choose the Native civilization (loosely based on the Aztecs and Mayans), you can attempt to set up a "High Native" civilization that is in essence a confederacy of all the Native tribes. The best part of diplomacy in Conquest, however, is given to the European powers. Assuming you start out as one of them, you begin the game as a subjugate to your mother country: nothing more or less than a colony. As you gain in power (and gold), your mother country will tax you more and more and interfere in your affairs and foreign relations. You can either submit - or, if you feel ready, declare independence and prepare for war. Fighting your mother country is far more difficult than fighting one of your rival colonies (at least, until you're significantly into the game and your rivals have upgraded their militaries). It takes strategy and planning to win. However, while it's definitely a challenge, it's not frustratingly so, and is one of the coolest innovations I've ever seen in a strategy game. If you manage to win, it is one of the most gratifying moments you'll ever experience in a video game. Also, the earlier you achieve independence (if that is your aim), the much better chances you have at winning in the long run.
CONS
The biggest problem with Conquest is that it can be very difficult to run with modern PCs (heck, even with some older PCs) due to the fact that it runs on DOS. I'm no computer programmer, but I've gotten some DOS games to work on XP/Vista; however, I haven't ever been able to get Conquest to work on either OS. For some reason Conquest doesn't seem to like them.
CONCLUSION
Conquest is a fantastic game that anyone with an older PC (or who is tech-savvy enough to get it to run on modern ones) should play. It's unfortunate that the programming is so finicky, as it makes this already-rare masterpiece even harder for people to play and enjoy.