The game starts well, and keeps expanding with new resources, technologies, and game areas. Having each key NPC available only a day per "week" adds a nice touch to keep you busy. Unfortunately towards the end of the game it gets rather boring, having to wait a week for each interaction with the NPCs.
Answering to @azoltan comment: the GOG version (as of June 2018) does include Skull Island (in the main package, not as a separate DLC).
The game quickly become boring, after one figures out that there is very little in terms of exploration, strategy, and quests.
