Each player has a game board depicting a smaller version of the island of Catan. You build by filling in the respective symbols for roads, knights, settlements, and cities. Building a road, settlement, or city costs the same resources as in the big brother version of the game, but the way you obtain the required resources is completely different. There is a legend tab for each map in case you need help remembering the building costs.
On your turn, you may roll the 6 dice up to three times by clicking the dice icon. After each dice roll, you may either set aside part of the dice (by clicking on them) or roll all dice again. Each side of a die depicts one of the island's resources: brick, lumber, wool, grain, ore, or gold. For example, if you roll 2 lumber, 2 brick, 1 grain, and 1 wool, you may build - i.e., fill in - a road and a settlement. You do this by simply clicking on the empty building piece in the map.
At the beginning of the game, the first road is already depicted as a built road (colored purple with a white arrow). Starting from this road, you continue building more roads. Each road built is worth 1 point. The order in which settlements and cities must be built corresponds to the number of points they are worth, from low to high. The points for building a settlement increase from 3 to 11, and the points for building a city even rise from 7 to 30. Since you can build a city or settlement only adjacent to an already built road, you might often find yourself in a situation where you wonder whether you should build a city, which is more lucrative but more difficult to build, or a settlement, which is less lucrative but easier to build.
And what is the task of knights? Well, each of the 6 terrain tiles depicts the contours of a knight. If you build (fill in) a knight, once during the game you may use the resource of a terrain hex where a knight was built in place of another resource of your choice. That is, after the third dice roll you may swap one of the dice so that the resource corresponding to this knight's tile becomes a "joker". Once you use a knight tile, you may no longer use it for the duration of the game. To make this easier to remember, click on the resource tile icon to invert it's colors.
After building, you enter your points in one of the 15 boxes depicted on your score sheet. The game ends after each player has finished 15 turns. The player with the highest score wins.
In the dice game described above, each player individually tries to get the best score; in the "Plus" version on Island Two, however, the players directly compete with each other (similar to the original boardgame version). Like in the board game, in the "Plus" each settlement you have built is worth 1 victory point and each city is worth 2 victory points. Furthermore, if you are the first player to build 3 knights, you may mark the "Largest Army" on your sheet, and if you are the first player to build 5 roads, you mark the "Longest Road." The "Largest Army" and the "Longest Road" are each worth 2 victory points; if another player builds more knights or roads than you, you lose the 2 victory points.
The first player to reach 10 victory points wins the game.
The building rules differ from those of the original game only in the following: If you have built roads next to several settlements, it doesn’t matter which one you build first. The same applies for cities. Knights can also be built in any order.
In the same way as in the original game, after rolling the dice you also may turn one of the dice so that the resource corresponding to an already built Knight is face up. During your turn, you may use as many Resource Jokers as you like, but don’t forget to mark them afterwards, indicating that they have been used (cross them out). You can use each of the Resource Jokers in the two deserts to obtain a resource of your choice. New is the fact that you may use the Resource Joker only if above it you have built two Knights.