As far as I can tell, the developer is just a very nice man(iac) who really wanted to share his vision of racing animals with the world. As you can tell from the video however, the results make it look more like someone handed him a bag of cocaine and a Quake mod and said "Go crazy."

THE ZOO RACE game is basically a foot race from start to finish.  The players must start at the starting line and then be the first to finish at the finish line. The goal is to win the race. There are many obstacles and strategies of each racetrack, however, to avoid or take advantage of depending on your player type.

... If playing on the “Hannah’s Heights” or when running on the “Moon” itself though, then be careful of the crows there and them dropping their crow poop on the ground towards you.  Do not mistake the food for the crow poop, because eating crow poop results in a speed penalty, which will slow you down. 

Sadly, I couldn't get the demo from the official site to load for me, but if you want to try your hand at this interactive anthropomorphic horror show, then by all means share your experiences. As for me, I'm going to keep laughing at the line, "I'm a horse now," while wondering what exactly Reuben was doing behind that desk.

Why do they send all the LSD-inspired stuff to me?