What you're describing I would categorize as "exploratory". Those games are fun and make good "big" games. The Portal series... early JRPGs... even the original Super Mario Brothers gave me that sense of not knowing where the boundaries are. You can have an exploratory game without much of a loop at all. But I also think exploration is unnecessary in some contexts. That's what I like about the field of games in general: they can look like a lot of different things and be good in a lot of different ways.