Thank you very much for your comment and for playing the game! :>
The advice about more introductory levels is nice. I guess we got too used to the knot and 2 characters mechanics while testing the game ourselves... and lost the sight of how it would look to the player, haha. We even wanted to add more mechanics like closing/opening doors, buttons etc. cause it all looked too simple... for our accustomed eyes.
(Well, mostly mine. Not brother's)
If we continue working on this game (we're not sure yet, maybe it's better as a short demo-project), we'll surely consider your words. So thanks for the feedback~