The difference between a game and a business application is the data. Most games don't need to store information about everything you've ever done; some games don't even bother to store your high score! Business applications rely heavily on data and lots of it. For example, a simple sales deal might involve:
Some contacts for key people who work there
An opportunity record to represent the potential sale
Multiple quote records for the various estimates you put together
Multiple quote line items on each of those quote records
Opportunity line items synced with the most recent quote
Pricebooks and product records that store the definitions and prices of what you sell
Opportunity contact roles to distinguish which contacts are decision makers
Sales team records to list you and your colleagues working on a deal
User records that represent you and your colleagues
Activity history for all of your calls, e-mails, and meetings
Don't forget the field...