Each thematic expansion comes with its own bag of tiles, in addition to the other components (like pawns and objectives, as well as other special components that are specific to each expansion, like the Canal End tokens, more on those later).
When revealing Route tiles at the beginning of each round, players must follow a pre-determined mix of tiles from the Core Box bag and the Expansion bag. Each column will still contain as many tiles as the number of square icons at the top of that column, just like in a regular game with the core rules, so that the total amount of tiles available to players during a game will stay the same (which keeps the duration of the game similar to the core gameplay).
Even if the total number of tiles available during the game will be the same, it will be a mix of core and expansion tiles, though, which significantly alters the flow of the game and the availability of specific tiles during the game and creates new, interesting challenges.
In the Canals Expansion, unsurprisingly, you will have to deal with the construction of Venice-inspired canals, bridges, and gondolas.
Your goal is to build Canals that are as long as possible.
—description from the publisher
Energy Expansion Your goal is to create a power grid by building Wind Turbines and using Energy Cables to connect them to Town tiles and bring them energy.
Additionally, the Energy Expansion comes with a few Objectives as well: for example, the Solar Farm want to be connected to Energy Cables on all 4 corners, while the Casino must have at least 2 electrified Town tiles around it.
—description from the publisher
Forest is one of the Expansion marked with "Easy" complexity: a good candidate to be among the first ones you try, or to play with inexperienced people. Your goal is to build Forests all around your network, while keeping them separate from each other.
Like all expansions, the Forest Expansion comes with a few Objectives as well: for example, the Witch's House does not want to be in the same row or column as a Lookout Tower, while the Camping Ground must have at least 4 Forest tiles around it.
—description from the publisher
Countryside Expansion Despite the cute looks and serene atmosphere, this is deceptively one of the hardest expansions! Your goal is to create big Pastures with lots of Farms, but you want only 1 Animal of each type in the same Pasture or you will lose points. In contrast to all other expansions, the Animal pawns you get are tied to a specific column of tiles you get from the central board during the draft phase at the beginning of each round.
The key to this expansion is to try to place routes, towns, and fences in a way that keeps fields containing animals of the same type separate to avoid losing both animals and points. Easy to say, perhaps, but succeeding may be more difficult than it sounds.
Just like all other expansions, the Countryside Expansion comes with Objective tiles: for example, the Vineyard wants to be part of an area of at least 5 connected Field tiles with no Animal pawns, while the Hills must have at least 3 Animals around them.
—description from the publisher
Desert Expansion Your goal is to create a Desert surrounding your regular tiles, placing Desert Attractions of the different types (Oasis, Pyramid, Sphynx, and Obelisk), connecting them to your regular routes through Desert Stations, and placing Camels to bring people seeing the attractions and gain a few extra points as well.
There's a special rule to follow when placing tiles in this expansion: When you place the first Desert tile of the game, it can be placed freely. All following tiles (either regular or Desert) must be placed so that at least 1 side is connected to a tile of the same kind.
Unsurprisingly, the Desert Expansion also comes with a few Objectives: for example, the Desert Market must be part of a route with at least 5 connected Desert Trail segments, while the Great Oasis must be surrounded by at least 4 Desert tiles... but it also counts as an Oasis Attraction!
—description from the publisher
Monument Expansion This expansion is pretty unique in that each player has an additional pawn, the Archaeologist, that can be moved around the landscape you are creating by using the routes you have placed by spending Action points. Your goal is to place sets of different kinds of Monuments (Arch, Temple, Tower) when you find archaeological sites.
Additionally, the Monuments Expansion comes with a few Objectives as well: for example, the Museum wants the Archaeologist to be on or around it at the end of the game, while the Castle must have at least 2 Towers around it.
—description from the publisher