Yes, I have played it with my 4-year-old, and she understood it, liked it, and won the game.
Leave the water tiles, number chits, thief, dice, development cards, and Longest Road/Largest Army cards in the box; they won't be needed.
Set up the land tiles of the island as usual.
Set aside some resource cards for the "random selection" deck:
- 4 each of stone, sheep, wheat
- 6 each of wood, brick
Shuffle this random selection deck and place it face-down next to the board. Leave room for a discard pile right next to it.
Each player takes the pieces of one color, and take turns putting three cities and/or settlements on the board. Players take turns putting one piece on the board until all players have placed all three. If there are young kids playing against adults, all the young kids place all three of their pieces before the adults place any.
The random selection deck is used instead of dice to tell which terrain tiles produce resources.
Each tile corner can have only one piece, but pieces need not be two hops away from each other; there can be up to six pieces around a tile.
Cities are no different than settlements, except that they need different cards to build. In particular, they only count as one "point", and they get only one resource card during production.
Players take turns. Each turn proceeds as follows:
Flip over the top card from the random selection deck and place it in the discard pile. This card tells which terrain types will produce resources. The player gets one card of that type for each city and settlement she has next to that terrain type. Other players get nothing. If the random selection deck runs out, re-fill it with the shuffled discard pile.
After getting cards, the player can trade and build as much as she likes. When she is finished trading and building, it is the next player's turn.
Building costs are as shown on the building cost card, except that development cards are not available. Cities and settlements can only be built at places that your roads lead to; they can't be just plopped down anywhere like during the initial setup. So you have to build roads before building new cities and settlements.
Trading resource cards between players is allowed, and she can also trade with the bank as usual: four identical cards for any one.
End of the Game
The first player to build four cities and/or settlements (not counting the initial setup) wins the game.