I've been coming across tons of games that have only one version, sometimes unity web, sometimes html5, sometimes just a windows build that have 5 links to windows, linux, mac, etc all pointing to that one version even though it only actually runs on one of those systems! If it's unity webgl just link it as such, there is a "web (other)" option for that, if html5 there's an option for that as well. There are thousands of games to play, it's important to link them correctly so we know which ones will work before taking the time to download them!