My first attempt at a strategy article. I'm not super-enthused about this title either, so suggestions are welcome.
This one seems long too, maybe I was too detailed. Perhaps if there are sections that can be removed or shortened without missing the point, you all can help me find them?
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I'll begin this article by defining what I mean by an "Endgame Plant." These are plants you don't intend to replace for the rest of the game. Generally any plant that powers five cities or more fits into this category, but depending on the number of players you can have more stuff that fits here, including plants that can only power four cities. A simplified version of this rule is that in a 4-player game, you need a plant that powers 5+ cities; in a 5-6 player game, 4+ cities will work, but you'd still rather have a 5+ plant.
The one exception is the 20 Plant (3 coal -> 5 cities). It's often accessible early, but if you buy it super-early, just be aware that more often than not its use over the whole game can cause a coal shortage at the end of the game, which means you might have to replace this one.
So how many power plants do you want to buy in a game of Power Grid? Ideally, as few as possible; best-case scenario is four. This is because at the end of the game you don't get anything back for plants that you've destroyed, which translates to cash. People who win Power Grid will almost always buy four or five plants over the course of the game, meaning that past your starting plant, you get one "mid-game plant" at most before you need to start thinking about endgame ones. This article focuses on the case where you are aiming to buy only four plants over the course of the game.
This kind of thing isn't always possible, since it requires a little bit of help from the power plant deck. If it's a 2-player game or you're on the China map, you can just forget about it.
There are two different situations here: it's either turn two or turn three; the analysis is different if you have two plants already. If it's turn three and you still only have your opening plant then one or more of these things might have happened:
1. I really hope your opening plant powered two cities. That's a much better place to sit than powering only one city for the first two turns of the game.
2. The board was expensive enough that you knew you weren't getting up to powering 3 cities on turn 2, so you decided to wait it out
What probably didn't happen is that you decided on turn 2 to gamble with the power plant market to put yourself in this situation when you could have gotten a midgame plant and powered three cities instead. I'm struggling to come up with a situation where this is a good gamble to make.
Buying an endgame plant on Turn 3 is a great move, but it's a common move, because you've been paid twice already and you have the money to support it better. This article wants to focus on buying an endgame plant on turn 2, where you're making a long-term strategic play, but sacrificing quite a bit to do so.
So here's the sitch: it's Turn 2 and you have the opportunity to buy a juicy endgame plant. This almost always means that if you buy that plant, you won't have enough money left over to build any cities, even if you get the plant at market price. In fact, in some cases, it's better to just use your opening plant again! If this is not the case, then one of these things might have happened:
1. Your opponents failed to bid you up on this plant to the point where this happens to you. They have nobody to blame but themselves (or each other, maybe)
2. You were the last person left to bid on a power plant and this gem just fell in front of you. You are very lucky and your opponents are probably saying dirty words to you. Smile.
Either way, you're sitting pretty. Enjoy your lead and don't look back.
For those of us who aren't as fortunate, you have a really difficult decision to make, and there are a lot of factors that weigh into it. You're sacrificing early income to skip buying a midgame plant that will eventually be replaced, so once you've decided if it's worth it or not to go for it, you'll want to minimize the damage and maximize the benefits. It's an aggressive play that can pay off if you navigate it well.
The Sacrifices:
You aren't getting paid much this turn, and early money is more important than late money. Your opponents are going to have a temporary tempo advantage on you. You're going to have less money for building cities, so if you're trying to contest a few key places to build, you've got an issue here. You can't let this make you fall behind even further because you can't afford to build cities or else you won't be able to recover.
If the connections are expensive to begin with, or you're only powering one city this turn, it's going to be difficult to build two cities next turn with the small amount you're getting paid if you already can't build one now. All of your income for the next few turns should be devoted to building cities, so make sure you don't leave yourself $1 short of your next city next turn or you'll be hurting even more. You'll probably be in last place for a few turns, so you'll be able to plan decently well. If you aren't doing two cities a turn until you need a new plant, you should reconsider this move.
The Benefits:
As mentioned before, you'll be low on cities so you'll have lots of benefits available to you. Make sure you use them! You won't be buying a plant soon so that one is already gone, and make sure you leave yourself enough money to pick a couple extra resources and continue to build, because when you move up in cities, you'll suffer in the turn order (you probably have the "best" plant out there). If your snazzy endgame plant is really efficient, make sure you realize you're throwing this advantage away as well, and make sure you capitalize on city building. Of note is the 30 Plant (3 garbage -> 6 cities), going first isn't going to make the garbage any cheaper as long as you're burning three each turn. Since you're behind in city building, that's where you'll need your advantage the most.
This is an aggressive strategy, which is more prone to working on cheaper/faster boards, so keep that in mind.
You also want to think about how you'll be positioned for a Step 2 Stall. Of course that's enough for a whole 'nother article. It's nice, though, to be positioned where you can either power five cities efficiently, or power six cities semi-efficiently. If thinking about this with your new endgame plant (plus your starter plant) makes you cringe, then either don't get the plant, or make sure your board position is such that you can prevent a Step 2 Stall.
This can be a high risk/high reward scenario, so if you set yourself up to succeed, you have a very good position for the endgame.