Sorry to hear you got hacked. Did you manage to get some of your cards back? I see you have roughly $1500 USD worth of cards in your account.
There such be a secure lock to the assets in the account and antitheft program should be developed.
Splinterlands does have a lock feature. When the Lock feature is used cards can not be sold or removed from ones account. They even allow us to pick the amount of days we want our cards locked for.
If I had to guess Its likely you clicked a suspicious link and gave your key(s) to a phishing site. Some tips for the future: (1) don't click link (2) if you must click link double check the URL (3) You should do a virus scan, change your Splinterlands/HIVE passwords (in that order) (4) don't use the same password for multiple applications (5) most importantly, don't give anyone your keys.
Thank you friend for your sound set of information, I will keep them in account. Hope you have a happy new year ahead.