Pretty sleek. It froze when I hit "r" though.

You can also remove the preplaced objects in the levels. Not sure if you're aware of that.

Also, consider having an icon onscreen to show what you've got selected currently.

Maybe arrange the icon tray a little better so that the mirrors are in a square shape.

Possibly add a tab to the right that indicates the menu can pop up.

Nice concept, I'm interesting in seeing how this will turn out. The robot talking to you is a bit annoying at the moment, but that's because you can't control the text scroll plus you kinda want to work the level at the same time. Maybe you could freeze and fade out the game while he talks (50% opacity black over the screen, for example) and make the text scrollable and able to be skipped by the player? That would improve it, I think.

was ist das?
:D