A grasp of psychology is also important in designing a good game; you want to know how players will feel at every point in the game. And it is vitally important that you can explain rules clearly in plain English.
The stomach's main function is digestion. It does this by: The stomach uses pepsin (enzyme) and peptidase (another enzyme) to break down proteins in your food. The acid released by the stomach doesn't break down food it only provides a good environment for the enzymes to work in.
In most vertebrates, the stomach is located between the esophagus and the small intestine. It secretes protein-digesting enzymes called proteases and gastric acid to aid in food digestion, through smooth muscular contractions before sending partially digested food (chyme) to the small intestines.