Josh Miller/CNET

Valve Software, which owns and operates the popular online game marketplace Steam, is transitioning from simply selling virtual worlds to helping game makers create them too.

The Seattle-based company announced Monday that it has developed a virtual reality system, called SteamVR, that it intends to demo next week at the annual Game Developers Conference. The system was announced in a casual two-paragraph blog post that detailed Valve's plans for the week-long confab beginning March 2 in San Francisco.

The company is also "actively seeking VR content creators" and asking developers to sign up to try the system at GDC. Outside of VR, Valve will be dedicating time to its specialized gaming-oriented operating system, called SteamOS, and its brand of console-style devices designed for living room gaming, dubbed Steam Machines.

"Steam is bringing the best games and user-generated content to exciting new destinations. At GDC 2015, we'll be giving demos of the refined Steam Controller, new living room devices, and a previously-unannounced SteamVR hardware system," the company wrote.

Virtual reality's looming arrival has been a running theme of the last few years at large-scale game and technology conferences. But 2015 marks the year VR is expected to spill over into the mainstream as high-profile consumer products become available to the public and media companies begin using the format of all-encompassing virtual worlds as a vehicle for filmmaking, live music performances and sports. By year's end, technology companies as diverse as Facebook, Samsung and Sony are expected to have full-fledged hardware on the market, while Google and Microsoft are both actively working on projects to overlay 3D images onto everyday scenery.

Sony's own Project Morpheus VR headset will take center stage at the company's lengthy GDC event next week and Facebook-owned Oculus VR is expected to be in attendance as well, with release dates for both products top of mind for consumers and developers alike.

Valve has been notably silent this past year regarding its Steam plans. After months of anticipation and rumors, the company unveiled SteamOS in September 2013 with the goal of expanding PC gaming beyond the confines of a mouse and keyboard.

To do that, it designed the Linux-based OS and its own custom controller and partnered with numerous gaming PC makers like AlienWare and CyberPowerPC to create dedicated living room hardware. Yet after it shipped 300 prototype Steam Machines to beta testers, in May the company pushed back the release dates for its Steam hardware and controller by a year. Valve also declined to host a second Steam-focused developer conference, the first of which took place in January 2014, and decided not to make a showing at this year's Consumer Electronics Show.

With GDC next week and the larger and better-known Electronic Entertainment Expo slated for June, it appears as if Valve is on track with a finalized controller design, new hardware prototypes and its answer to VR competitors.