The second game of the series contains much more detailed and different new mechanics. Build a great internet cafe. Don't let street thugs and mobsters take your money. They can even throw a bomb inside your cafe.
You can attract more customers on rainy days. Increase the skills you want to develop from the tech tree. Will you become a business prodigy or a brawler skilled at protecting his cafe?
You have to earn money to pay off your brother's debt! Keep guards. Prepare meals for your customers. Install generators for power outages. Improve computers. Purchase game licenses. Delight customers. Turn a ruin into a great cafe. As a decent person, he can proceed normally. Or you could get involved in completely illegal business.
Hire employees for your cafe and treat them well.
Remember, the customer is always right!