I really enjoyed your game. In the beginning, even after reading the tutorial, I wasn't sure where to go or what to do, but I figured it out. I thought the symbol on the doors that showed up was where I was supposed to go. Maybe if you could see from which door you picked up the item would would be better. However, I noticed, that whenever you become invisible, you will stay invisible even after the effect disappears and it carries on to other levels as well. The teleporting was sometimes annoying, especially when I teleported right to a group of enemies when they were charging their attacks. Maybe some design changes on later levels would be nice to make it more interesting. Money could have more uses as well. Another thing, I noticed when I went to the main menu and wanted to start the game over it put me in a level that was higher than the one I was in originally. I wanted to read the tutorial, but to do that I had to restart the whole game.
I got to level 7, but when I was near the edge and enemies attacked me, I fell over the edge and couldn't do anything. I went to the menu but when I started the game again, the level counter went crazy, and my character wasn't in the room. After that in the menu there wasn't any music and when I tried the game again It was completely black so I had to close the whole game.
But overall very nice game.