I did like the puzzle ideas, I’d play more of this! Implementation wise (except for the obvious lack of exit mechanic, which you shouldn’t omit even in demos, not everyone knows about Alt+Tab/F4/Enter and your game defaults to fullscreen), I have 2 pieces of feedback:
One is simple, when forward and turn are pressed at the same time, turn should take precedence whenever there is a traversible tile at that direction and not only when forward is blocked. Even turn always preceding forward, which is even simpler to do, would be better than the current mechanic if properly timed by the user.
The other might not be very straightforward. The fast turning of the cubeworld feels very satisfying at first but is also super disturbing after a while, it can induce dizziness or stomach turning. Maybe solved by slowing down the animation, but that could be frustrating, or zooming the whole level out? Don’t know, but you should definitely test to find something that works.
That’s all. Again, concept is nice!