Right now? Just load up OpenTTD and have a ball.
First time I played Transport Tycoon was on my 486, I got a demo of the original game on a floppy disk out of some PC game magazine. Looking back, it's amazing how much game play fit onto a 1.44MB floppy disk. I ended up purchasing the Deluxe version on a CDROM. I ripped the CD and have kept an image of it ever since, which came in handy when I found OpenTTD and wanted to use the original graphics and content. Chris Sawyer and the OpenTTD devs are legendary in my mind.