Solarus is an open-source Zelda-like 2D game engine written in C++. It can run games scripted in Lua. This engine is used by our Zelda fangames. Solarus is licensed under GPL v3.
You might be interested in our fangames created with Solarus:
Zelda Mystery of Solarus DX, our main creation.
Zelda Mystery of Solarus XD, a parodic game released on April 1st, 2011.
If you want to create your own games with the Solarus engine, see also Solarus Quest Editor, our Solarus game creation software.