Transport Tycoon/YMMV


 * Goddamned Bats: The AI companies, town councils, and those UFOs that appear and attack your (and only your) trains and buses.
 * Good Bad Bugs:
 * In the original game, building a long enough tunnel would cause the cost to run negative, and you would make over a million dollars/pounds/whatever. Bad in that if you earned enough money, your cash would flip into the negative, and you would suddenly be millions in debt. Fixed in subsequent versions.
 * In the original, with level crossings, whoever owned the railway owned the square. This meant that you could screw over AI road construction by laying rails over their roads and destroying the road. Fixed in subsequent versions.
 * The original game included two minor glitches in the way it worked out signalling. A railway depot counted as a normal piece of track for signals, and the signalling algorithms didn't distinguish between the tracks of different companies. On their own, these bugs had no real effect. Together, however, you could build a loop of track between the end of a rival's railway station and the nearest train depot. Any train that entered the station would then trigger its own signals, and it would never be able to escape the station.
 * Memetic Mutation : "The all important cheesy midi goodness", in reference to its catchy oh-so-early-90s game soundtrack.