Unity makes software tools used by some 4 million developers to build video games. Virtual reality could turn it into a $1.5 billion business.

Unity is getting ready for the spotlight. It’s been conservative in the past about taking outside investment, at least by tech startup standards. It has raised only $17 million, even as it has grown into an 800­ person company with operations in about two ­dozen countries.

But Unity is currently in talks with investors for a round of funding that could value the company at $1.5 billion, say people familiar with the matter. The round is expected to close within weeks.