The Railroad Tycoon franchise is on sale. That's Sid Meier's Railroads!, Railroad Tycoon 2 and Railroad Tycoon 3. 2 and 3 were made by PopTop Games, an indie studio who were also known for the original Tropico and its (not-as-good) sequel Tropico 2: Pirate Cove, before they got eaten by Take-Two Interactive and folded into Firaxis Games under Sid himself.
Tycoon games are often really poor games in general, but the Railroad Tycoon series is up there with the Rollercoaster Tycoon series for actually being good games. Railroad Tycoon (2+3) focuses on the transport of goods, railroad and station management, the stock market, investors, bonds, etc. It's like you're actually managing a railroad business although there is a decent bit of streamlining so it's not just a dull experience.
Haven't played Sid Meier's Railroads!, but I can say that both 2 and 3 are really good. 2 is 2-d isometric (although you can rotate the map) but the graphics are still nice, and 3 is in full 3D. 2 is the more challenging game, as some additional streamlining found in the third game can be taken advantage of. Still, for both games, there's tons of replayability given the tons of scenarios and different tiers of achievements for the scenarios and the free-play modes and etc. etc.
The bundle is on sale for ~$7.50. Just 2 and 3 together costs the same price, so the bundle is getting the newer Railroads! game for free.