Tunngle used to be a VPN service, much like Hamachi. It allowed users to connect to other computers over the internet, but in the fashion of a local subnet by means of a virtual LAN. This allows many (especially older) games to be playable over the internet despite the fact, that they were merely designed to be played on a local network. In contrast to Hamachi there were already existing channels intended for certain games, e. g. a channel only for Counter-Strike. When joining such a channel, the user got automatically connected to the corresponding VPN and could host or join games, which were available for everyone on the channel, just like there were on a LAN.
Since 30.4.2018 the service is discontinued. The carrier named new data security laws as an obstacle, that prevented him to continue the service, as that would have required too much of an effort.