Thanks for playing! I do plan on adding a miniature tutorial in future versions of the game. Until then, I'll gladly expand the help screen to provide more useful info. Also, yeah, tiles will become obscured by "fog of war" when not in line-of-sight. The effect isn't very pronounced in this version, but in more cramped levels of the dungeon, line-of-sight will be an important game feature.
Thank you so much for taking the time to leave feedback! It always really helps. :D