Webmahjong is a browser project for playing Japanese mahjong without installing an app. It includes four-player riichi mahjong as well as other variants, and provides a rules guide and glossary. For a first session, it helps to separate learning the tile groups from learning when a hand can actually win: matching a complete-looking shape is not the only rule to check. The project is shared here as an entry point; consult its current guide for the modes and controls you want to use.