And what is it to be exact

Tropico is like Sim City, but you're in charge of a Caribbean island. The game has scenarios and missions, but it's best feature is the sandbox mode where you can set the level and play for as long as you want.
You have to build farms and logging camps to get your economy rolling and eventually you'll be able to make your island a haven for Tourists.
Another great part of this game is it is set during the Cold War, so your political opinions and diplomatic actions can change how the US or the USSR think of you. This can be from large amounts of aid or invasions and overthrows.