Most online games only work if the person you want to play against has the same system that you have: console, PC or smartphone. There is, however, a growing library of games that offer what is often called cross-play. This lets you play with people on different systems.
These games are a good way to extend the list of friends and family that you can play with. It also makes it less critical which system you have in your home, even if your friends have a different one.
This list includes 100 games from the last 24 years, with 3,476 likes. They come from a range of different genres and play-styles and are all good games if you want to play with people on different systems.