A mysterious software firm is buying more than 67,000 acres of land in Northern Nevada with plans to showcase its technology there. Blockchains LLC — whose website does not list any executives, a phone number or clear explanations of what its software does — is acquiring the land at the Tahoe Reno Industrial Center. It buying a landmass triple the size of Summerlin, Las Vegas’ largest master-planned community. The seller, developer Lance Gilman, says a major announcement from the company is expected by the end of February.