Here is a description from Spielbox:
A couple of months ago, a mini edition of Flusskoenig (River King) was released. The new release of Flusskoenig "Director's Cut" expands the game with several new components that were originally planned for the first game but ended up being cut so that the game duration didn't run too long.
Still, as is usual with NMG games, Flusskoenig "Director's Cut" will run at least 3 hours (for comparison, Flusskoenig clocked in at 90-120 minutes). Once again, the idea of the game is to transport wares via ship. The players lay out a river network at the start of the game, one that can twist and turn as desired and provide either 'realistic surroundings' or a 'fantasy world'. Players then get money and can buy expensive ships, ship enhancements and branch offices - the things that bring the points necessary for victory. Locks, toll booths, fog and low water make sure that the riverboat captains have to work hard.
The "Director's Cut" version expands the game with new river tiles with additional hazards, new ship types and wares, a deck of "truly evil" action and event cards, and other accessories.