Alone is one of the three skins released in the Meme Mania offer. It could be purchased as part of an item deal for a limited time in early December 2017.
Alone could be purchased for $4.99 in a deal that included 3250 coins. It could also be purchased for $19.99 in the "Best Deal!" which included the Rage skin and 1800 DNA. Alone was not available for individual purchase and may not be available for purchase in the future.
Details of this skin can vary depending on location, platform or time.
Note: Alone was released again for a limited time as part of the All the Internet Things offer in mid November 2019. This time Alone could be purchased individually for 5100 coins.