Holiday Palace Casino
SihanoukVille (and Cambodia's) longest running casino.  Across from Victory Beach.

Fortuna Casino
on the Golden Lions Circle.  Formerly the Golden Palace Casino, has completely renovated, and boasts the largest casino in town.

Kampong Som City Casino & Hotel
SihanoukVille's newest casino.  

We can't say here, but a few bars around town have Texas Hold'em Poker games on certain nights of the week.