There is a good foundation here, but there are a lot of little technical things that reduce the "feel goodedness" of the gameplay. Some other comments have pointed them out already (such as no health indicators for enemies), but another big one is the camera placement when the character jumps. It is both so zoomed in, and so close to the bottom of the character, that it's impossible to see where you are about to land (and if there are any enemies or portals there). Great job!