Press [Shift] + [Alt] +C during game play.
When researching an item, click on the speed bar from 1 to 4. Your employee will research the item faster and sooner or later you will get the item you desired. You now can use that item in your zoo.
For example, you're researching the Animal Theater and want to get it faster. Click on the speed bar to maximum speed. Wait a few minutes and you should get the Animal Theater.
Items that are bigger may take longer to reasearch. The Animal Theater, animal exhibits, etc. may take up to 5 minutes if the speed is at 4. If you chose a food it will maybe take up 2 minutes for research. Gifts may take up 3 minutes.
You can also unlock special terrain maps by completing scenarios. For example, Rainforest Zoo will unlock the Rainforest zoo terrain.
You can unlock animals such as the Asian Black Bear, Przwlaski's Wild Horse, Albino Gorilla, Chinese Alligator, etc. Research the strongest fence and go to the bottom of the list of animals. All the ones after the Chinese Alligator are the ones that can be unlocked unlock during scenarios. Rainforest Zoo has the Przwlaski's Wild Horse and Asian Black Bear. Condition:Critical has the Albino Gorilla and Asian Black Bear.