They have provided me withdrawal address, but they did not provide me IPs.

However, how its possible that someone can have access to my link if the link is generated
in browser thru https secure connection and unique identifies my account?

Hello,

I was playing games.bitcoin.com (I was provided https link) https://games.bitcoin.com/?account_key=d35d372dde... and I sent another deposit of around 0.11 BTC and then it was
too long time to wait for confirmation and I decided to play later.

I closed the window and in about 10 hours I returned back to URL to play. I noticed that my account was "password protected" and I contacted support. After questioning me (to confirm that I'm account owner) the password protection has been disabled. And what is the surprise - my balance shows 0 BTC.

Support has told me that funds were withdrawn. I sent email to games@bitcoin.com and never received
reply.

How hacker can access my account with balance within 10 hours after I deposit funds there?

Its seems for me that hacking occured on the bitcoin.com side. Be careful as you can lose your money easily with games.bitcoin.com due to lack of security.