This is my personal choice of hard to find but noteworthy games on the marketplace.
Crazy Rider | Windows Phone Apps+Games Store (United States)
Reflexions | Windows Phone Apps+Games Store (United States)
Space Shift | Windows Phone Apps+Games Store (United States)
Amazing Penguin | Windows Phone Apps+Games Store (United States)
Barnstormers | Windows Phone Apps+Games Store (United States)
Pollushot | Windows Phone Apps+Games Store (United States)
Shel's Shallow Skies | Windows Phone Apps+Games Store (United States)
Woods Guard | Windows Phone Apps+Games Store (United States)
SimplePhysics | Windows Phone Apps+Games Store (United States)
Loot Grinder | Windows Phone Apps+Games Store (United States)
Tower Orb | Windows Phone Apps+Games Store (United States)
9 Iron Ninja | Windows Phone Apps+Games Store (United States)
Have fun
BTW this list is not sorted best to worst, it's random
PS
If you know some other good games that hidden deep on the marketplace please post links to them here
Crazy Rider | Windows Phone Apps+Games Store (United States)
Reflexions | Windows Phone Apps+Games Store (United States)
Space Shift | Windows Phone Apps+Games Store (United States)
Amazing Penguin | Windows Phone Apps+Games Store (United States)
Barnstormers | Windows Phone Apps+Games Store (United States)
Pollushot | Windows Phone Apps+Games Store (United States)
Shel's Shallow Skies | Windows Phone Apps+Games Store (United States)
Woods Guard | Windows Phone Apps+Games Store (United States)
SimplePhysics | Windows Phone Apps+Games Store (United States)
Loot Grinder | Windows Phone Apps+Games Store (United States)
Tower Orb | Windows Phone Apps+Games Store (United States)
9 Iron Ninja | Windows Phone Apps+Games Store (United States)
Have fun
BTW this list is not sorted best to worst, it's random
PS
If you know some other good games that hidden deep on the marketplace please post links to them here