Is there a reasonable easy way to implement free movement in a tile-based isometric game? Meaning that the player wouldn't just instantly jump from one tile to another or not be "snapped" to the grid (for example, if the movement between tiles were animated but you'd be locked from doing anything before the animation finishes). I'm a really beginner with anything related to game programming, but with the help of this site and some other resources it was quite easy to do the basic stuff, but I haven't been able to find any useful resources for this particular problem.

Currently I've improvised something close to this: http://jsfiddle.net/KwW5b/4/ (WASD movement). The idea for the movement was to use the mouse map to detect when the player has moved to a different tile and then flip the offsets, and for the most part it works correctly (each corner makes the player move to wrong location: see http://www.youtube.com/watch?v=0xr15IaOhrI, which is probably because I couldn't get the full mouse map work properly), but I have no illusions that it is even close to a good/sane solution. And anyway, it's mostly just to demonstrate what kind of a thing I'd like to implement.