a few points.
1. lose the arrows and magnifying glasses. Is this an escape game or a flow chart?
They take away all semblance of immersion.
2. LOVE LOVE LOVVVVEEEE the 3-d aspect and especially the fact that you can turn objects around 360 as you examine. ;)
3. Lose the ' I CLICKED HERE IT DID NOTHING HAHA' white ring of death on the cursor. See above for why. trust me, the people you want to love your games will do so, if you do what I'm telling you.
4. I've played a lot of these, and the ones that stick in my memory the most are deeply immersive, with rich story, and quite arrowless.
5. Lastly, try to make the interface elements less intrusive. If you are aiming for immersion, obvious interfaces are not the way to go. Although, Skutnik's games are a venerable exception.