The "hot corner" menu was a cool idea but I think most will agree that it isn't very practical for the playing style we're familiar with. It slows things down and can become inconvenient when accidentally brought up. This is one feature I would just scratch altogether.
I think people would be very happy if you gave us an Options menu with some of the features below..
Mouse Options
-Click-to-attack - Use mouse click to attack
-Click-on-target - After a spell is cast an additional click is required for the target (for those that preferred this method)
HP/MP Options
-Traditional Display - Xenimus display (vertical bars with top-to-bottom descending HP/MP, easier to judge damage imo)
-HP/MP Placement - Left/Center/Right Bottom/Top
Menu Options
-Menu Hotkeys On/Off - (S) Stats, (I) Inv, etc.
-Menu Display On/Off - Menu is display on screen (pic for reference)
These are just a few options that I believe would be pretty easy to implement and would allow us to set the game up to play how we'd like..