How do I explain Dreamchaser? And how do I convey how much I thoroughly enjoy it?
Well, let me give it a shot.
First of all, the game is a "setting free" ruleset. Normally, I don't really like the rules without a setting book. However, Dreamchaser is so much more than that. It's the first game that I can honestly say would be CONFINED by a setting. Because Dreamchaser is really only limited by your imagination. Now, a lot of settingless games would try to tell you the same thing, but this game is the first one that really encourages you to not only dream up something big, but to do it WITH your players. It's not only the GM who gets to design this world. The players are just as (if not more so) responsible for creating the setting as the GM.
Let me explain a little how this works. First, the players decide on a Dream (a game) they want to play. It could be, "Save the Princess", or "Prevent the Singularity", or "Defeat Organized Crime", or (my favorite) "Make the Perfect Sandwich". Every player throws their idea out there and then you all vote on the one you want to play. If your idea isn't chosen, never fear! You still get to decide your Milestone! These are personal achievements you want your character to obtain on your journey. Each character gets one! Decide the order the milestones are achieved, make some characters (an easy process) and watch your GM squeam as he tries to put all of those ideas together into a coherent story. (Actually, this is my favorite part as GM. And the players really, really help you along in this effort. More so than many an RPG).
Add in a very simple, yet deceptively deep system (roll 2d10 and get under various benchmarks on EACH die) and you've got yourself a hell of a game.
Dreamchasers is a wonderful, wonderful game that is truly unlike anything else you've played. It's a game that will come out again and again on my table, especially if another game has ended and nothing new is lined up or we want to play a game when one of the crew can't make a session. In my experience, this game is not a one-shot, but more like a 2 or 3-shot. However, the more players you have, the longer it will take (more Milestones = more adventures). With that being said, you could definitely make it a long term campaign. You're really only limited by your ideas and if you have a whole table contributing great ideas, you've got yourself long-term fun.
You won't regret getting this game.