Highly polished and challenging Zelda fangame, Lost Isle
http://koti.welho.com/pranta18/index.htm

An Untitled Story
Non-linear, open world platformer with puzzle elements. Great soundtrack as well.
http://mattmakesgames.com/games/AnUntitledStory.zip

Gravity Bone
Very short (<20mins) and sweet game experience based on the Quake Engine.

Metroid Confrontation
Relatively short but again polished 2D Metroid fangame, based on a larger project to remake Metroid II
http://metroid2remake.blogspot.co.uk/p/metroid-confrontation.html







