Allow to name armies and heroes. It is fun. And don't take much memory for servers.
Make movement grid little bit brighter or outline those white stripes with black stroke. It isn't hard to look at them, but it certainly is tiresome to load your eyes so consistently to see them clearly.
UI is ok, though, even if I'm totally fun of minimalism, current ui seriously lacks any fantasy vibe in it. Even blue color scheme is too cold for it. Dark fantasy could use some brown, dark orange or neutral grey.
Speaking of UI - you have event handlers on buttons. So, if they are clicked, it is 100% sure clicked. Yet, if clicked-hold button and moved cursor away, click still counts. For me, it isn't problem. But I know people,who actually does such things to "think" one last time before making decision, and if changed their mind - moved cursor and canceled click. UIX is so fun. )
Probably already known, but - chat window must be paginated or scroll able in own window, not on whole browser div. Else it's really uncomfortable. Also, when chat gets clustered, it is incredibly annoying to do so, when you want to add location in to chat. (That also is a problem, as in smartphone, I can't click on location to add it to chat... window is on whole screen.)