It's kind of sad, really. I wanted to give it a chance but right away when I read the description about how it won't work for Chrome I was a little let down. People who use Chrome should be able to play your game just as much as any other user of Firefox. What if someone doesn't want to download the extra software to there unit or they are in a situation where they might not be able to then they can't play it at all. If you can't make a game that includes all users than why create that game? I will give you one star because you did what others hadn't so far as I've seen on here do. You put a warning about the game not working. The games that iv'e come across with the same problem don't even bother to put that in the description.

Uncontrollable. Mouse sensitivity needs to be far, far higher. My mouse keeps going out of the window trying to do a simple turn. Unplayable in the current state.

You fell into the same hole I usually do for Ludum Dare. I've only finished one myself (look for Toy Soldiers on my profile). You tried to make something that was complicated from a programming standpoint and therefore barely got it done; with substantial glitches and oversight and had little to no time to make tutorials or good level designs within the time-limit; ultimately creating something that is very confusing to the point of impossible for the average player (a lot of controls; no in game tutorial to ease the player into how to properly use them; instead just being dropped into a level and having to read a text box to figure it out).

At this point; it's not really enough of a prototype for me to say much. Spend a couple more days on it to get a tutorial to the point that a player could understand it more easily and I might have more to say.

Finally got used to all the controls and managed to beat the first level. Then I wandered into the "delete save" portal, not knowing what it would do.

Mouse controls kill this game. I think you've got a pretty good start, though, and I do love 3D physics (even in Banjo Kazooie: Nuts and Bolts). The trick I used on that first level was to start the blueprint off at my destination using the scrolling, and then build towards myself. Obviously it's good that your green block cursor is always connected to the existing blueprint, but how come it can go diagonally from the blueprint when you can't place blocks there? And the game only responds to shift and ctrl on the left side of the keyboard.

You should be able to move the green cursor block with the keyboard. 6 keys for six directions.

I found myself wishing there was some way to return to the hub from within a level.

I think it's worth continuing, but definitely make sure you add sound!

First, I absolutely hated it, then I failed miserably at constructing and thought "I'm gonna beat it despite the terrible controls" and then I noticed that the blueprints could be manipulated with the mousewheel. I started liking the game. I understand that it still is a very early version, but in my oppinion, the first thing to be improved is the controls (something like an mmo camera movement, dunno).
All in all I feel that it's quite a solid concept and with some challenging puzzles I feel like it has the potential to become a fun little game :).