Virtual Reality development is commonly paired with game engines like Unity and Unreal Engine, but a developer does not need an engine to develop VR space. There are tools like A-Frame, where anyone can code HTML/CSS sites to incorporate 3D entities with VR capabilities without downloading a game engine.
A-Frame houses HTML/CSS libraries that can be used to code, view, and share VR experiences available to everyone. A-Frame makes learning the HTML/CSS easy with several open source sites available on GitHub to reference when developing a project. Some projects may be too complex for a smaller project, but will contain many valuable lines of code to understand and manipulate. There are currently few videos to help develop, but if a front end developer reads the source code on the examples they could create a quality Virtual Reality experience.
WebVR applications are great ways to easily share work with friends by sending them a url for quick access. The A-Frame tool gives more room to create an easy way to share Virtual Reality experiences. Their blog is a great place to explore and share new content, and ways to approach development roadblocks.
Since the url can be viewed cross platform, this is great for people with the low cost headsets, more expensive headsets or no headset at all. If a developer wanted to share the experience with their friends, they could send them the url and it could be viewed in any browser. Another viewing option is the VR view. If the link was opened on a mobile device, the VR icon in the bottom right will put the experience in a split screen to be viewed with a Google Cardboard or Gear VR. If an Oculus Rift or HTC Vive was connected to the computer, the site will recognize the connection and the VR icon will put the experience on the Head Mounted Display.
If you are interested in developing virtual reality experience but do not want to mess with game engines, I recommend looking into A-Frame.