There's a lot of those type of games out there so narrowing it down is tricky. I know a lot of the games are based on the mc codes script. There's an older GPL version and a newer commercial one I think they sell that includes a bunch of features... You can get them here...
MCCodes.Com - Your Source Code Stop
Support forum...
CE's PHP-Games Your Online Game Developing Resource
Or if you could tell us more about it, we might be able to narrow it down.