I guessed I was supposed to create flows between the plus and minuses of matching colour.

If that's what you were going for, it could work, but it needs something extra for it to work as a puzzle. Obviously you'll have your own ideas, but a few things spring to mind, like limiting moves/block placement, coloured tiles permitting same coloured flows to pass while blocking others, coloured metal blocks that disappear only when the corresponding coloured plus and minus are connected, having the player lose when the wrong plus and minuses connect.

now updated!

Couldn't figure out what the heck to do... Nice music though. Why does everyone else always manage to get nice music for their LD entries?!

I played it when it had no tank and it was fine and dandy, so... what's up with the tank? Is it there just to control the camera? (I can still place and take blocks away with my mouse so... really, I dun like the tank)

Anyways, I liked your game, especially since it's a puzzle game and I haven't seen one quite like it. And I see you've put some effort in pathfinding and particle effects as well - all in all it's a nice entry! (without the tank!)

The mouse isn't supposed to do anything now! The tank is there to create/destroy blocks, which adds interesting mining and maze elements to the game. :-)

Is the archive corrupted? I can't extract it.