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the hill giant's back is a little bumpy...
ALL of the animations are a little bumpy, but I fear there is little to be done to avoid this - since NWN animations are put together from several "body parts" instead of being directly drawn in 2D, they will always looks a bit worse - even in NWN.
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and it is dark yellow (I suppose it has such colour in NWN but I find it weird)...
I see nothing wrong with this, but if it is changed to a bit more greyish tone, its all the better.
Now, lets see the previews one by one.
Hill Giant: looks good, but the skin color could be changed to soft grey instead. Also, it would be essential to allow them to use a club.
Minotaur Prince: great one. Both the animation and the coloring looks nice, the multiple weapons are also appreciated.
Gelatinous Cube: niiiice
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Balor: the basic animation looks awesome, yet the flames on the sword, wings and the whip are lacking. WoRm, you said these will be added MUCH later - why is that, if I may ask? Also, what's wrong with dual wielding?