The Nordenfelt demo got its overdue update. The last version dated back to 2011. So it did not represent the current development state very well.
Right now I'm working on level 4 and further equipment. The tech tree structure will influences the order how to tackle the different levels. E.g. some enemy types are immune to the primary weapon. So you have to unlock the right equipment to wipe them out. This is the basic idea which I'm going to refine within the next days.