Cheats for Transport Tycoon (PC)
Start at the sea level, and build the biggest tunnel you possibly can. If the tunnel is more than 300,000,000 and you have less than 1,000,000, the money will be added, rather than subtracted. To ensure that your opponents do not make any money by means of road transportation, locate a particularly lucrative road route belonging to the computer, find a bit where the road goes straight, lay a bit of railway track over and bulldoze it down. Strangely, the computer doesn't rebuild it, even if it previously owned it.