Recently, another version of js-dos (browser version of dosbox) was released. The new version has the ability to play the legendary DOS games over the network (via the Internet).The list of available games is small (DOOM, DOOM2, WarCraft, Duke Nukem 3D), but it will grow.
Network games are completely free, the only difficulty is to correctly go through all the steps to establish a connection and find an opponent (channels in telegram and discord have been created for this). Watch a tutorial video on how to start a multiplayer game using DOOM as an example.
The project is completely free and does not contain advertising, enjoy: