An early morning fire at the Top Ten Bingo hall in Ystrad Mynach was deliberate, say Gwent Police.
Two fire crews, from Caerphilly and Cefn Fforest, were called to the building in Bedwlwyn Road at 4.25am on Thursday April.
A spokeswoman for South Wales Fire and Rescue said firefighters successfully tackled the small blaze which was around an external fire exit.
Nobody was injured and the fire was extinguished before any major damage was caused to the building.
The fire is being treated as deliberately set and officers are investigating.
If anyone has any information about the incident, or if anyone saw anything suspicious at the relevant time and place, they should call Gwent Police on 101 or call Crimestoppers anonymously on 0800 555111.