Railroads defense
First off its a game not a simulation so incorrect for realism in fact cartoonish, yet the feel of a rail empire is there. The settings are there to make this thing a bear to win so the challenge is up to you (a bonus) by the setting you choose.
The maps can be made for infinite playing fields (no two landscapes ever) Yes its a money game so get busy early and make alot for best chance at a win usually by buying all your opponents stock before the game time period ends.
I can play on graphic settings set to the limit but start in low and see if your system responds. I bug 2K every year to give additional maps but no.
The big news is that there is a Mac version just out. It has tempted me to buy a Mac as Mac graphics rule. My hope is a resurgence due to the Mac offering may lead to an expansion.
Spend some time learning it and you will find its an addictive little game. I have enjoyed Railroads for many years, even bought several and handed them out to friends to try. Give it a chance and learn it before rushing to judgement.