Oookay a lot of things to improve:
first make enemies moving.
second level design:
Going somewhere just to be told i need to find a key and walk ll the way back to the start to then walk the samw way back... not fun. especially with no challenging enemies. "if you take the wrong portal go back 1 level" the previous level was just walking without any enemy... not fun!
The game is ok. I felt like I was playing a retarted version of mario. I got all the way to the white screen and couldnt get any farther cause I had no idea what I was suppose to do. My biggest suggestion would be that if you insist on having long runs to have some clouds or somthing in the background so it actually looks like the player is moving. There are points in the game when I didnt even know I was moving like the part where it says run and eventually keep going before that. And please change the music or atleast give the option to cut it off or change it to something else.