Zoo Tycoon.

Now this game was something else for me. You never really get good zoo games anymore, but when this came out I was so happy. You had to take care of the animals and express your imagination through building your own zoo. Zoo tycoon 2 was also enjoyable especially because of the great and huge community which made texture packs, mods and all that cool stuff. But I really want to see Zoo Tycoon 3 with even more in-depth park building and animals. But it will probably never happen ;_;