Some game expansions are worth buying, and some are not. Before buying, consider:
- How frequently you play the base game
The less frequently, the less you require an expansion.
- How often you have already played the base game
If you don't play the game frequently now because you're tired of it, but you played it to death when it first came out, an expansion might rekindle interest in the game.
- How rich is the game play experience of the base game?
A game that's already wildly imaginative and plays differently each time doesn't necessarily need an expansion.
- How much game play the expansion adds
The price should be proportional to the change in the game play.
- How disruptive the expansion is to the base game
Does it offer more options, or does it entirely change the game mechanisms? More options is good if you like the base game but need more to keep it stimulating. New and changed mechanisms means a new game, which you must want to choose to play in place of playing the base game.
All of these questions lead to the ultimate question: how often will this actually hit the table? My track record for expansions varies wildly:
Age of Steam, Power Grid, etc. (maps): Train and other connection games that don't come with a randomized board setup can use expansion maps. These don't hit the table often in my group, so a few expansion maps is sufficient for us. Beyond that is a waste.
Agricola: Agricola comes pre-packaged with expansions, including the various decks. It needs no further expansions. I have successfully avoided them.
Alea Treasure Chest: This is a box with small expansions for seven Alea games, of which I own six of them. We use to play a lot of Puerto Rico, and I created my own expansion buildings for it, so I was open to playing the Nobles expansion. It's good, and will probably come out again.
I haven't tried the other expansions yet, but I suspect we will get to them. We don't play the other games all that often, so I don't know how often the expansion will come out even if the base game does ... unless the expansion significantly improves the game. In which case we will no longer play the base game without the expansion.
Apples to Apples: If you play often, additional cards can be fun. However, A2A is designed well, so that you don't really need expansion cards. No two hands are the same.
Blue Moon: I didn't find the base game all that interesting. I didn't try the expansions, but I doubt that you can play the base game too often without them.
Carcassonne: The standalone games such as Hunters and Gatherers and The City don't need - and don't have - expansions (there's a very small tile expansion for H&G). The base game required some expansions to spruce up some imbalances in the scoring. I don't know much about them, however.
Chess: Changing anything in Chess means playing a different game; Chess is Chess. Chess means memorizing openings and very specific evaluation strategies. Any and all expansions to Chess are simply abstract games played on a Chess-like board with similar rules to Chess. I prefer the variants.
Cosmic Encounter: Cosmic was built to have expansions, since the game is designed to be wild and full of surprises. The more the merrier. However, I don't like several of the expansions, notably the ones that disrupt the game play (moons, variable hexes, ...).
Cuba: The designer sent me a few tile expansions to the game. I don't play frequently enough to judge these. They don't disrupt the game, but I wouldn't have gone out of my way to buy them, either.
Dominion: Dominion is already a fantastic game, and several of the expansions are fantastic, if slightly-less balanced. There comes a point, however, when you have enough already to make every game different; at that point, the only reason to buy expansions is for the same reason you buy packs of Magic cards: you want a particular card. Don't do it. Pick two expansions and no more.
I'm going to violate what I just said by buying Prosperity; however, I could easily give up Seaside.
El Grande: I tried the King and Intriguant variant several times. The concept wasn't inherently bad, but some of the cards were annoying, and wouldn't you know it, every player played on of those cards at least once a round. In the base game, those cards can only come up once or twice. So I banned those cards in the variant.
Turns out that we simple didn't play El Grande enough to warrant the expansion at all.
Homesteaders: An amazing game space which I haven't come close to exhausting. But I think there's room for a set of expansion buildings. Just one.
Magic: the Gathering: This game, as all TCGs, is built around the concept of expansions. Luckily, making some cards rare meant making other cards common, and thus worthless. You can pick up thousands of "worthless" cards for a song, after which you don't need any more expansions.
The Pillars of the Earth: I bought the expansion, and the group played it once. We don't play the game enough to warrant it. Actually, I've grown sour on the master building drawing mechanism, so, unless this expansion fixes that, I probably won't be playing it.
Power Grid (deck): Unlike the maps mentioned above, the deck provides variant plants to acquire during the game. While it did, it had hardly any noticeable effect on the game.
Puerto Rico: I've already created half a dozen expansions to this game, and they keep the game from going stale.
Setters of Catan: The expansions to this game were a mix of additional options (Seafarers) to disruptive (Cities and Knights). I like C&K, but it's a different game, which doesn't come out all that much anymore (we played it to death). I didn't think Seafarers was worth the money, after playing it once. The 5-6 player expansions made the game long and cumbersome.
What's the moral of this post? While the Tribune expansion looks tempting, I don't need it.