If I was to be stranded on a desert island, with a game and gaming equipment of my choice, I think I'd have to pick Galactic Civilizations II as the game. Of course, I'm assuming the island doesn't have the internet, or at least no form of human contact is allowed (I believe that's the point in any fictional 'desert island') – after all, being stuck on a desert island with just World of Warcraft for company does actually pass as a holiday for some people. But out of all single player game features ever created, I would say that Gal Civ 2 has possibly the greatest longevity I have ever seen.
Gal Civ 2 is a turn-based strategy, population management and exploration game – some call it a '4X' game – '4X' meaning explore, expand, exploit and exterminate. It means that you take full political control of a race of beings, and decide on everything they do economically and politically, generally with the goal being to expand your race's influence as far and wide as possible through any means, be it purely diplomatic, militaristic, or anywhere in between. But unlike many other games that try to give you a free reign to complete your goals but ultimately make one way of doing things much the same as the other, in Gal Civ 2 you really can potentially complete campaigns any way you want – bribe your allies to wage war on your enemies for you, or just stomp on their faces yourself, it's all possible, and it all works.
The problem that this creates though is that in providing you this very rich, open environment, you're left with an overload of information and options. This is just compounded by that fact that the in game tutorials are rubbish – just text and videos, with no interactive element. I would just prepare to be bewildered for the first hour or so, whilst continuously referring to the manual – things such as the economic and production system aren't particularly intuitive (you tax people to pay for factories to create resources that you can use to create or enhance in game units and buildings... ngh), but once you get going with the game the pieces slowly drop into place, and it all adds to the longevity of the game in the end.
As I mentioned earlier, Gal Civ 2 will last you a while. Ignoring the single player campaign (which has an excellent story), you can potentially play a single skirmish for days, possibly weeks – the maps can be huge, with even a small one costing you an afternoon. Couple this with the wide range of possible tactics and you've got a game that will last a very long time. The only real downer on the whole experience is that there's no real multiplayer – you can play set scenarios and upload your score to the internet, but it's not a proper multiplayer game. Having said that, I guess that with more than a couple of players on a big map, you could actually die at your computer before anyone wins the game... What makes it an extra shame is that you can custom build your ships, allowing you to have your entirely own designs (adding/upgrading weapons and sensors as well as many other options, including purely cosmetic ones) and the thought of rolling over my enemies with a pimped out battlecruiser of my own design is really quite appealing.
Gal Civ 2 is a big, complicated game, but ultimately very rewarding if you're willing to get through the initial state of bewilderment. If this review has piqued your interest, then it's almost certainly worth a try. But if reading the manual is against your personal moral gaming code, then it's probably best to look for something a little more action oriented.