I just checked and the AUR version is way outdated. You can instead grab the tar.gz from the website and run sudo python setup.py install
I’m not sure the lutris: url handler works out of the box with the tar.gz, it should but I haven’t tested it.
Other than that, the only funky dependency is python-yaml (which I plan to drop in the future releases).
Since I don’t plan supporting ARCH any time soon, somebody should step up and package a proper stable release for AUR (or the official repos)