I've never seen anyone who gambled at work yet but when the Zynga Poker on Facebook was a big trend, many employees do play that game and I am actually one who did that too. It's not gambling because there's really no money involved unless you buy the chips just so you can play the game more the whole day. That I never did.

Don't do this both, it's just a waste of time, we have our breaks, and we can check our social media or gamble for a bit on our smartphone if we want to but when we sit down in front of our job, we should be focused.
Is solitaire counted here because I play a lot of this game while working since I always have some waiting time when waiting my clients feedback on submitted proposals.

You are lucky in your company that facebook is allowed to access back in the days when Zynga poker is popular. Smart phone is not that popular that time which means there’s no other means to play at work than using the PC. Seriously, Who have the courage to play at work here especially gambling while you will risk tainting your career once you are caught. Worst is you will be banned on companies that has connection to your current employer.
Do you gamble on solitaire? I think you are referring to playing a game but not gambling. That thing could not be allowed as well as it makes employees unproductive but gambling is quite different, it has an after effect that an employee might be disturb when he loss and will not be effective the rest of the game, more so if the act has been repetitive already, it's already causing a lot of resources of the company which does not produce output.