User interface improvement — Powargrid Steam update #527006

Hi, Michiel here! After watching a few videos of people playing Powargrid, I noticed that they were often looking for a place they could place a certain building, moving the mouse around until they found a good spot where they could afford to build it. I've been working on this game so long, I mostly just know without even thinking about it -- so that was a good wakeup call that something could be improved there. I'm now trying out a little visual aid, by highlighting the tiles you can build on and "lowlighting" (is that a word? de-emphasizing!) invalid tiles. For me, it's REALLY weird to change anything to the core visuals after staring at them for years -- but I think this is going to be an improvement! I've just set the new build live, so everyone should be receiv...