Each VR platform has different controllers. Quest uses hand controllers with grip buttons. Valve Index has finger tracking. Some systems support hand tracking with no controllers at all.
If you write code that says press button A on a Quest controller, that code breaks on every other platform. Your game becomes locked to one device.
Input Abstraction Layers
Instead of coding for specific buttons, you code for actions. You define jump, grab, or shoot as abstract actions. Then you map those actions to whatever inputs each platform provides.
An input abstraction layer sits between your game logic and the physical controllers. Your code says the player performed a grab action. The abstraction layer translates that into squeeze the grip button on Quest, close your fist in hand tracking, or pull the trigger on Vive.
Handling Missing Features
Some platforms have capabilities others lack. Index controllers detect individual finger positions. Quest controllers do not.
You design your interactions around the lowest common denominator, then add enhancements for advanced systems. A climbing game works with simple grip detection everywhere, but shows individual finger animations on Index.
Testing Real Scenarios
When Soren Dalsgaard built his cross-platform training simulator, he discovered that grip strength varied between devices. Players on Index could barely trigger actions that Quest users activated too easily.
He added sensitivity calibration that adjusted thresholds based on detected hardware. The same grip action felt consistent across platforms because the code compensated for hardware differences.
Input abstraction requires upfront planning but prevents rewriting interaction code for every new platform you support.