Starting from an existing eclipse installation, you can install Xturtle by using the updatesite
During the installation, you have to trust a certificate named
cn=Sebastian Tramp with the Thumbprint
D4 30 D2 EF 31 78 40 DF F8 DA 6A F7 F7 EC 89 BB CF 92 44 82. This may change in the future.
Since Xtext is a dependency of the Xturtle editor, you need to install it as well. For those not having an eclipse, the easiest option is to use the latest itemis distro where Xtext is already installed. If you have an eclipse installation, you can use the composite Xtext update site
for installing the necessary Xtext components.
You'll know that the editor is working, if you open a .ttl file and you are asked if you want to add the Xtext-Nature to the project. Further, on invoking code completion (ctrl-space) in the first line, something should happen...
For more information on features, usage notes and technical background, have a look at the wiki.