WASD + mouse definitely, if it comes even closely to the awesomeness of Counter-Strike 2D. Drakilor scripted a mouse movement for an oooold version of Mythic, I'll dig around in backups and see if I can find it.
Pre-Post Quick Reply Edit: It seems this is what I thought of.
http://forums.graalonline.com/forums...ad.php?t=72985
Has great detection, and should be editable to remove the click-to-move part.