First, I have to say that the UaW:EA vehicles are awesome and would be cool in an fps. Second of all, I'd have to say that the hierarchy vehicles are much too massive to use in Blockland, although I would like to see a large detailed build based on a walker. Lastly, most suggestions that come from other games/movies/etc. are rejected due to the fact that they are overused. Your best bet is some cool gun or vehicle or something, if anything at all (unless you make it yourself).
