Transport General ($4.99 > FREE)
This version is iPhone only. A pretty good, but flawed Transport Tycoon clone (HD version is also available for $4.99). UI is not very good, I've read about some problems later in the game about pathfinding and crashing. No iAPs. So the game could use some updating and polishing, but for free it's worth checking out before the forthcoming Transport Tycoon remake release.
Favorites: The Quest Gold + expansions, Mission Europa Collectors Edition, Ascension, Jet Car Stunts 2, Junk Jack X, King of Dragon Pass, Kingturn series, Mecho Wars HD, Mini Dash, Mos Speedrun, Ravenmark, Sonic series, Fall of Angels, Highborn, Solomonís Keep / Boneyard, pixel art games, remakes and ports of classic games.