Probably not quite what you mean but Foundry VTT makes playing Role Playing Games like Dungeons and Dragons or Pathfinder online much better. Most competitors are cloud hosted and all but the basic features are locked behind a subscription whereas Foundry is an application you buy outright. The catch is that it still needs hosting somewhere so those with any technical wherewithal either host it in Oracle’s Cloud since “always free” tier VMs are ample to run it or else self-host on a Raspberry Pi or similar. Those who don’t self-host have no other recourse except to pay a housing service like Forge a monthly subscription for a limited amount of disk space