You do not say why you are looking for a computer simulation. The  Income/Outcome Business Simulation is a classroom game used for developing finance literacy and business acumen.  Simulation run-time is anywhere between 3 or 4 hours, and 3 days depending on complexity of the simulation dynamics. 

Everyone does start at the same position, and in each business cycle there are multiple (complex) decisions - throughout the cycle, teams will have to revise their strategy and decisions in response to the industry (i.e. the classroom).

You may find that Income/Outcome employs more game theory than some of the computer simulations; decisions made by one team will impact the other teams in the competition.   Instead of all teams competing against one computer, the teams will compete against each other. This may or may not be what you are looking for.