So long as you have the Nvidia App, you can use RTX Remix to remaster your old games. As Nvidia points out in its post, RTX Remix could already improve the particles that make up explosions, flames, and smoke effects. Until now, RTX Remix interpreted particles as path-traced to amp up the lighting, making the particles more vivid. If you want to update particle effects of a game with RTX Remix, you have two options. On the other hand, if you know what you're doing and want more granular control, Nvidia has an option for you via the Nvidia RTX Remix Toolkit.