itch.io

I'm voting for this :)

I haven't test any of these but there is a slot machine plugin in the rmmv dlc folder dlc/KadokawaPlugins_New/js/plugins. Also you can check this one by the Unpro pro https://www.rmf.gg/resources/slot-machines-plugin.1215/

Suggestion : Maybe add a joker card just in case somebody need it. Also commonly the king of heart have a sword in his head because there is a story behind it about some kind of suicide.