A game of Via Nebula starts with a board showing a hexagonal grid, some production sites with a few available resources on them (wood, stone, wheat, and pigs), building sites in various areas scattered over the whole board, and a lot of mist.
Turn after turn, players have two actions at their disposal from these options: They may clear the mist of a hex to create new paths of transportation, open new production sites, open a building site in a city, carry resources from any production site to their own building sites, and, of course, achieve a construction. Resources and paths through the mist may be used by all the players. This initially induces a kind of cooperation, but eventually other players will take advantage of your actions!
To achieve a construction, you fulfill a contract on one of your cards. You start the game with two contracts, and four more contracts are available for all players to see and use on a first come, first served basis — and that's where the cooperation abruptly stops. Additionally, most contracts have special powers that are triggered on completion.
The game ends when a player finishes a fifth building. Opponents each take two final actions, then players score based on the number of cleared hexes and opened production sites and the point value of their contracts, with a bonus for the player who ended the game.