The fifth survivor is really a dick move. Also the controls are really horrible. I'm playing on a german keyboard. It's horrible to use "Z" together with the rest. Please add "Y" for the same as "Z". Also the jumping doesn't feel right. Seems like you can't jump anymore once halve of the player is over an edge. But you know, that's normally the point where you press jump as you run over the edge. Here the player just falls down.

So, yea, all in all not really fun to play.

-Character seems good
-horrible control choices, its no fun when you have to switch between X, Z and the arrow keys
-level feels lifeless

This would be alright if not for all the stupid fake walls/floors/ceilings. (Fr'ex, to anyone playing, the fifth survivor in level 1 is in the left-most wall; hug it as you fall.)

Other than that, the gameplay's cool enough, if a bit DIAS in nature. Starting out with a zoomed-out view of the map for a few seconds to give the player time to plan a route would help a lot. (Though, of course, only once the fake walls are gone. Seriously, why do people do that nonsense?)

It would also be cleaner if the level ended when the lava killed a builder, rather than having to wait for it to kill the player; scroll the camera over to the dead builder to show where the player failed, then restart. A reset button would also fix it, but that's not actually necessary if you just implement this.

I can only find 4 survivors on the first stage, and I'm unclear what the point of the bomb is. Set it on a rock, stomp, and send it flying up into the lava? Why?

The graphics and simple, but not a big deal, the animations are smooth and the sounds okay. Music is nice, not intrusive.
But I'm finding no real point in game play.