I'm puzzled about this kind of remark by my opponent ...

So I was playing this Russian guy and he beat me for the 2nd time in a row, but before preparing himself for the final blow he wrote "Зверь" in the chat box ... upon a quick Google search, I learned that's 'animal' or 'beast' in his language. My question is: Is this some kind of creative insult? Or has that word some hidden connotations which only native speaker would be aware of?
It is not nice being told off by someone who doesn't speak your language, and I would like to be sure what he/she meant by that. -_-

Usually it means a "beast" as appraisal. Though it doesn't make much sense if it was him beating you. This word is almost never used as an insult unlike "animal" ("животное").

@DVRazor: thank you, you actually confirmed what I was thinking!

he still had the question mark behind his rating but is obviously much stronger than me. I still made him mess up in the opening, so he had to move his king several times. Maybe it was more intended as a joke than a mean-spirited one-liner (it's too ambiguous for a true insult).

Meh, one-word rudeness isn't that bad. I'd find it a friendly attempt to start a conversation if my opponent said something like "damn!".

maybe he was giving himself some light encouragement, 3rd person style
"com'on beast we can do this,"