So I've hired a 2d artist for my game which is very good at drawing and asked him to draw characters in a particular style that I like, basically telling him "I like this characters, please take a lot of inspiration from them".

Really, the thing that is similar is the style, but obviously I have the fear that the original "inventor" could potentially sue us.

Here is the one of the original pictures:

And here is what my artist drew for me:

Obviosly the the reason why I can't hire the original author is that he's too costly for me, it's not affordable to pay him.

As you see the style is really similar, but really there isn't anything "copied", my artist just recreated new stuff in his style.

What do you think? should I be worried?

Thank you,

Leonardo

Inspiration comes from many different places, including other artists. As long as you don't directly copy their art and put it into your game, you should be fine. 

 The 2 don't look similar to me in any way, but i second Tom Sloper you can be sued for anything, in this case i highly doubt the case would have any grounds, but consulting a lawyer is always the advice for this kind of dilemma if you want to be sure.

 My personal opinion is you have nothing to worry , and i doubt the style was invented by the creator of that image , and i also wonder if he was as worried about HBO and George Martin suing him for depicting The Hound.