very cool... maybe even cooler if you could see a bit of light at the end of the tunnel in the first drawing? A dark tunnel is more of a threat, making the backside drawing less of a surprise.
The tunnel itself could be a bit closer too.
I agree with some up there, having a train chugging up to the tunnel in the front, blissfully unaware of what is waiting for it on the other side plus having the tunnel be see-through, so you can see nothing from the front but see the train coming towards the tunnel from the back would make this an instant 5$. It's a really great idea with average execution as is. Please resub man!
i personally luv it back and front it has a certain feel in the front calm, kinda leaves you to think what you will. then the back gives you a meaning the without doubt is different from what anyone would have inferred I want this shirt now!!! wish i made it 5$