This is one of the best games of all time.
A seamless blend of tactical RTS and vehicle simulator, it pits you, a naval carrier/factory and a crew of dead soldier stored on computer chips against a mad Cabal of arms dealers and evil politicians hellbent on making war against a world that has been completely demilitarized. Your journey takes you through a chicane of 20 islands in the South Pacific as you investigate and dismantle the Cabal's operations.
The storyline, written by famous comicmaker Warren Ellis and narrated by legendary Doctor Who veteran Tom Baker, is very deep and engaging, and makes you genuinely care about both your crew and vessel, and the helpless world you are protecting. I won't give away any spoilers but suffice it to say there are far worse things hiding in those islands than 20-year-old tanks and gunships, and by the end you'll experience quite a few genuinely scary moments.
The gameplay is, as I said, quite seamless, without a single bug. Steam integration could be better however: the Overlay isn't working so you can't take screenshots and it doesn't log your game time (which is why it says up there that I've played 0 hours of it), and as of yet there is no Steam Cloud support. We can only hope. However, the root game is quite well-rounded and optimized. The AI, especially that of your uploaded soldiers, is competent without making you feel unnecessary; there's always a situation where you're better off taking the wheel yourself. Graphics-wise, quite amazingly, the game looks rather good, especially given how old it is, and it will run without a problem on any machine.
You have absolutely no reason to deny yourself this amazing game.