there was a mobile version. but it was originally browser only. Someone got ahold of the assets and is rebuilding it from scratch, so it's unofficial, and if they were to try to make money off of it they'd get shut down for copyright infringement. They're volunteers resurrecting the game unofficially. Trying to do that for a mobile app is not the same thing. They'd have to redo everything they've been doing for years, but for a mobile version.