The official Crystal snap is available

During the Snapcraft Summit Crystal team released the official snap package of the Crystal language

https://snapcraft.io/crystal

On Ubuntu 16.04 or later, you can install the Crystal snap with the following command:

sudo snap install crystal --classic

Snap uses the "channel" feature to release multiple Crystal series concurrently. For example, without specifying a channel, currently Crystal 0.29.0 will be installed. But if you want to install 0.30.0-dev, specify the latest/edge channel as follows:

sudo snap install crystal --edge --classic