Custom system, but well organized. I haven't played it, but giving 5 stars because it's complete with rules, setting, maps, tools to quickly construct scenarios, put together NPCs and good tips for new GMs.
Definitely leans towards creative role-playing and story telling and not for crunchy combat. Good for groups that want to have an adventure, rather than groups who want to compare how many hitpoints their weapon can dish out per round. (You can probably sense my own bias here)