Would you look at that, an asymetrical PvP game.
It's pretty fun, expecially Cirno's moveset and how your drags' distance affects the speed.
I think all it really needs is a quickswitch hotkey for Cirno because going back and forth between looking at then selecting a skill, and look at the enemy then using the skills... well every tenth of every second count you know. Especially in that singleplayer mode.
How about being able to switch Cirno's skills with the Mousewheel?