The elf is cute, although flat (which I like too, and there's a nice flipping animation).
Didn't have another person to enjoy the game with unfortunately, but I think it's an amazing concept. Cool to see the pre-attack animations as they mitigate spam-clicking and motivate the S.A.N.T.A player to try and predict the elf's moves. I think a way to set up obstacles (temporary walls for example) or traps would improve the gameplay further.
Also, perhaps there could be a way to defeat S.A.N.T.A? Maybe by making his attacks backfire if the elf does something (placing the present in the way?).
The S.A.N.T.A is a bit too low-poly for my taste, and the shading is kinda dark on him. I liked the pixel art though, and it's interesting to see 3D models and flat pixel art combined in one game.
Nicely done!