Currently attacking works by holding down shift. This makes the character take out his sword and swing it in the direction that the player moves the mouse.
Combat will be based around quickly determining a strategic spot to move to, moving there, and then slashing enemies. You are vulnerable while moving.
Also I am rushing the art. I started to draw sprites for the character swinging his sword in different directions, but scrapped them and am now just drawing a line from the character to the adjacent tile. Crude but effective... I'm running out of time now that school has started.