The Dream was a standalone mini-supplement to the 4th Beluaterra Invasion in my online game BattleMaster. It was an interactive fiction game, without much action and combat. There were a few quests and there was a small game-world to explore and discover.
It was a 3D mini-game available for OS X and Windows. While the game was a standalone program (i.e. you download and install it), it was tied into the BattleMaster game and linked to player accounts there. If you had a character on Beluaterra, you could even get in-game rewards for him (but you could play for fun even if you don't).
You could dream once per day, and a daily dream cloud last up to 30 minutes. Estimated play time until you had seen everything there is to see was about 4 hours total.