What's the best Android app for trying virtual reality without buying a headset?

Cardboard is Google's platform for bringing accessible virtual reality to Android smartphones, designed for users who want to explore VR without investing in costly hardware. By pairing the app with a low-cost cardboard viewer—available from various manufacturers or as a DIY kit—it enables basic VR functionalities like watching 360-degree videos, viewing VR photos, and running lightweight interactive demos. Specific features include a calibration tool to optimize the viewer for different phone models, integration with YouTube VR for streaming content, and support for third-party apps via the Google Play Store, such as virtual tours or educational simulations. In real-world scenarios, this makes it suitable for casual users trying VR for the first time, students exploring virtual field trips, or individuals creating simple VR content. However, limitations are evident: graphical fidelity depends heavily on the smartphone's display and processing power, and the experience lacks advanced features like motion tracking or high-end graphics found in dedicated VR systems. User feedback reflects this balance; reviews indicate that while many appreciate the affordability and ease of setup, common critiques point to a stagnant development cycle, with requests for more updates and expanded app libraries. Minor imperfections include occasional lens distortion on some viewers and a interface that can feel dated compared to newer VR platforms. Despite these drawbacks, Cardboard remains a practical entry point for budget-conscious VR exploration, especially for short sessions or introductory purposes.