Thinking From the End In keeping with established principles from a lot of games, in Dominion, you want to 'think from the end'. In essence, focusing on what you need at the end of the game will help you figure out what you need to do earlier on. Anticipating what moves are going to come down the pipe, from both players, helps you determine what to do now.
How this applies to dominion is this: there are
four game-end conditions (sometimes only three, sometimes just two; but four are possible). Your goal, in any game, is to manipulate both the scores and when the end of the game happens. It's all nice and cute if you get out to a big lead, but can't seal the deal by ending the game, or if you can build a deck that does anything and everything, but can't grab points at any appreciable rate with which to catch up.
Overarching Principles Working from the very end, we'd set up the following principles:
1. When on your turn, you see the opportunity to reach one of the end-of-game victory conditions, take it. Absolutely take it. (Note: if there are multiple ways of doing this, which is relatively common, any of them works).
1a. This is sometimes very difficult to calculate. Thus, it's usually really good to know what piles are liable to end for a three-pile ending, where the goal-posts are for reaching an insurmountable points lead, and most importantly, the scores of all players, in order to work things out more quickly. As much as possible, take your time and calculate things out.
2. If you're absolutely certain that a particular play will allow the opponent to end the game with a win before you get another chance to do anything (i.e. you three-piling while behind, buying the penultimate duchy, which will be the third pile, whilst he has a KC'ed Merchant Ship in play), don't make that play.
3. And it starts to get fuzzier...
Let's assume we're still in the deep endgame for a moment (and by deep endgame, I mean the game might be ending at any moment now):
At this point, you have two competing variables. You want to minimize the chance that your opponent can win on their next turn, but at the same time, maximize the chance that you can win yourself on your next turn.
The Nitty-Gritty For instance, you want to think twice about buying that conspirator/grand market/insert engine component here, because it will make it that much easier for them to three-pile, and you lose. At the same time, don't be too too scared of grabbing things, if you need them to miss out anyway. Here's where
taking risks really comes into play. If buying that card gives them a chance to end it, but not buying it means there's no way you'll get a big enough turn to be able to win yourself on the next turn (or, earlier on, in the near future), then you just have to roll the dice and hope they don't get a good enough draw. Because if they do, you were lost anyway.
It's really important to note that the point spread is really important, even when considering such pile-depletion options. If I buy a [generic engine component], it's one buy closer for your opponent to empty out piles. But it's also one fewer buy for you to empty piles, and if you've got the lead, you have to add in all the buys/gains for him to retake the lead ON TOP of those needed to empty the piles in order to be able to win.
Specific Deck Types Money Money decks largely play themselves. There's some anticipation in terms of variable-VP alternate green cards, etc, etc. But there's fewer relevant decisions. Having said that, there are still lots of things you need to be watching here.
If you're playing a BM-BM matchup, watch the points, and watch your deck quality. Luck in the draw will be big, but also extremely important is to know when to turn green. Typically here, there's two things you're gunning for. Running out the provinces (colonies if applicable), or grabbing half the VP available. The former tends to be more important than the latter, but you need to watch out that you're not going to stall too hard, especially when decent alternate VP options exist. You don't want to green too early, and get choked out, but you also don't want to green so late that you are blocked from buying the important cards for too long. The provinces get a little bit of preference than the half-the-VP in this matchup, because coming from behind by buying cheaper stuff is just so much less money efficient. Keep PPR in mind more here than anywhere else, but you also want to keep track of relative strength of decks, duration cards in play, and how many of your opponents' (and your own)
If you're playing in a BM-vs-Engine matchup, things are a good bit different. Watch out to see how they're going to come back on you. Is it by tapping in the large potentials of variable VP cards? Then you have basically two options: buy out ALL the provinces (so spend a lot more time building up than normal), or get a lead and then block those alternate VP hard to close their lanes off. Facing more of a conventional engine? It's a race for either half the VP (usually recommended) or all the provinces. The big thing to note in either scenario is that you have goal-posts which are moved well apart from a the BM-BM matchup, and you need to change your play accordingly. Rather than gunning for four-provinces ASAP, you probably need to settle into more of a long game. Typically you're going to be faster than the engine, and so you need to get that lead, and then cling to it, blocking off their avenues of escape. If you can't maintain lead OR deck quality (and engines are eventually almost invariably of higher deck quality than BM, it's just a question of if the game will last long enough), you should've gone engine.
Engines Engine vs. BM. Presumably you have a reason you went engine. There's a few different kinds of engines around here, and they play a little differently. Typically, most engines nowadays seem to be centered on getting some great big mega-turns. And in most engines, what you DON'T want to do is cash in your chips too early, by hunking off a bunch of green too soon. Sure, it can level the scores a bit, but your deck is likely not so resilient to green, so you're trading away your big deck-quality advantage. In these kinds of decks, you usually don't want to touch green until very very late - typically the turn that you want to end the game on, though sometimes you might just pull the trigger when it gives you a decent-sized lead, if you're worried about them ending it on you too soon. The big thing, though, is to hold off for more or less as long as you can.
On the other hand, you might be just playing a cards/actions engine which has some nice attacks to it, or just because it's a nice little chain of cards that are very easy to put together. In these cases, you tend to use a greening strategy much more like BM's. Typically, you green a bit later than BM anyway, especially if you have some buys handy to be able to knock off some province+duchy or even duchy+duchy turns if you're behind far enough. But you can't really afford to wait around forever if you can't get a real big mega-turn. And if you have attacks to choke out your opponent, you can be ok to come back for a decent while anyway.
Engine vs Engine. Typically, these are the most complicated endgames in all of dominion. Again, you want to keep rule 1 in mind all the time. And you want to keep in mind that your opponent is also keeping that in mind. So you want to take very careful stock of what exactly your opponent can do on their next given turn. This is typically easiest when they're drawing their entire deck, but the important things are how many buys (or gains) and how much money they can grab. You also want to know how reliable it is that they get all this stuff. Basically, you want to know how much damage they can do, and try to make sure it's not enough to kill you. Something really important to keep in mind is with gains - if they have a strong enough engine, they can gain a bunch of things mid-turn, then draw them, then use them, increasing the amount of stuff they can pick up to more than what might otherwise seem apparent. Keep out of range of them, while increasing your own range of destruction. And snap down the win as soon as you can. Very often, the three-piles (perhaps on random-seeming things) are really important here. And, as mentioned before, you want to keep of a lead when that starts to become a big factor.
An Example I'd like to check out the end of
this game against -Stef- to show you a little of the ropes here. By turn 12 or so, we're drawing large portions of our decks. Actually, he's about drawing his entire deck, whereas I'm drawing large chunks of mine. But what's important to note here is that he has 4 pawns; I have 6. I have 4 highways to his one. And he's got 4 silvers and 2 coppers with 3 peddlers to my much much less money (well, it's just my original coppers, the 7 pawns, 2 peddlers and the 4 highways). He also has a trading post, which he might be able to use to get a little more cash than me. So he has a lead in points, a lead in money, and he's much more likely to be able to draw everything than me, but I have more buys and more cost-reduction. Okay, I play my next turn, and at the end, I've got 4 highways in play, all 7 coppers, my potion, and a couple of peddlers for cash. This gives me a LOT of options. I can't really go for a game-end at this point though, because pawns are the only pile out, and whilst scrying pools are down to 2, I can only nab one of them. More importantly, I'm 9 points behind. So while I actually COULD have ended it, I couldn't do that AND take the lead. So instead, what are my options? Well there's lots. I end up using my 5 buys on 2 provinces, a border village->highway, and a couple of (free) islands. I could have bought the scrying pool, and really, I think I ought to have, because with only 5 buys, there's no way he can pile out on the next turn - espcially when he'd have to take the lead back from me, and 'waste' at least one of his precious buys on a pool. The Islands are nice in that they're free points and also actions, the BV is another action, and the source of +actions lets me have some options on my pawns, and the provinces give me the lead. Also, even though there's only 4 provinces left now, I know I'm ok there, because he doesn't have enough buying power to use all the buys to grab them.
On his next turn (13 for those following at home), he doesn't quite get through his whole deck, but ends up with the highway in play, 12 coin, and 5 buys. I have a 7 point lead. He's actually in really bad shape. He needs lots of points, and can't manage all that many (more highways would have REALLY helped him out). And he has to worry about my piling out. You may think he actually also has to worry about me getting the last 4 provinces - but he doesn't, in fact. Well, not really anyway. I would have to use every drop of coin in my deck, AND be able to use 3 pawns for coin and 3 pawns for buy, in order to get all the remaining provinces. If I get that perfect a draw, well, he's going to lose anyway. So, but he does buy a province, which we might already question, because it gives me some options there. And he buys an island over a duchy, and then three peddlers. The problem with the three peddlers is that it makes piling out a MUCH easier job for me - my best chance to pile is by grabbing BVs to pile them out and piling something else as well, and 3 fewer peddlers means that 3 more of my gains can be VP - which helps me out a ton. If I were him, I'd probably recognize that to have a good chance, he's going to need to get a really really big turn on his next turn, which means more highways for him. You think he needs VP too, but it's a lot of money to take the lead, and that's not going to leave him with much chance to do enough on his following turn. He almost NEEDS me to have a dud hand. So I would go for probably the 4 remaining highways here. Maybe 3 and a duchy, maybe 2 and a BV->highway and an island, something like that. And then soak peddlers with the extra buys. The idea is that he probably needs me to have a dud hand (and with 7 coppers, a potion, 3 estates, 2 provinces, 2 islands, and a couple stables I need to have connect with treasures to do anything, this is possible. But it's unlikely it happens to me on consecutive turns. So he probably needs to play for a really big turn on his next.
On the last turn of the game, though, I don't have a dud, and I roll through a lot of stuff, get all my highways in play, and run out the Border Villages (and peddlers, concurrently), and then pick up loads of duchies - way more than I needed to overcome my 1 point deficit - to win. If you look at it, I could also have grabbed all three remaining provinces, had I played my pawns differently. But it didn't really matter, at that point, as I calculated one win and took it.
Combo Combo decks... it really depends on the combo. Basically each one has its own way of playing, and it has more to do with that particular combo works, rather than some over-arching principle of combo decks. Golden decks chew up provinces until the game is over (or golds if you're far enough behind or something). Native Village/Bridge tends to not want to pop until it can either have all bridges on mat, or secure game victory. Chancellor/Stash runs for 4 stashes, then races green. Point is, it really depends on the deck.