Finding flight simulators that present a complete package is a rarity as some handle great with a solid interface but the missions are lame or the graphics may be excellent but the game is over almost before it started.
There's the Freeform game, with unlimited money -- that is, no money worries at all -- and all animals and buildings, etc., available. Pick a region anywhere in the world for your zoo and start building.
Not that Kameo doesn't deserve that accolade on its own, because it really is an enjoyable game. As the titular heroine Kameo, you have been betrayed by your own sister who has chosen to ally herself with the sworn enemy of all Elves, the Trolls.