DIAGNOSTIC ORDER
Test one input cause at a time.
Update the Early Access game to 0.6.39 or later, then relaunch it. The official hotfix says unrecognized joysticks and keyboards should no longer register as valid input devices.
Start a new run with only a standard keyboard and mouse connected. Release W after the opening prompt and check whether the character remains still.
If the issue remains, quit completely and disconnect non-standard HID devices before relaunching: gaming keypads, extra controllers, macro pads, CAD mice, and similar peripherals. This is a reversible diagnostic, not a required permanent setup.
If movement is now normal, reconnect one device at a time and retest. That identifies the device or driver injecting the forward input without forcing a full reinstall.
If the bug remains with only keyboard and mouse, open their vendor software and switch to an unmodified default profile. Older player reports document Razer Tartarus and Swiftpoint remap conflicts; they are fallback evidence for pre-0.6.39 or remaining cases.
Only after the input test should you verify game files or reinstall. Reinstalling alone did not clear one older report, so it is a later diagnostic step rather than the first fix.
If none of these checks work, report the keyboard, mouse, every attached HID device, vendor software, display mode, and Early Access build in the current bug thread. The developer asks for the device when a similar issue remains after 0.6.39.
WHAT SUCCESS LOOKS LIKE
After updating and relaunching, the character stays still after you release W. If a remaining input conflict returns when one peripheral is reconnected, record that device and report it instead of treating the older workaround as universal.
VERSION BOUNDARY
The official 0.6.39 hotfix says the majority of auto-walk and not-walking cases caused by unrecognized devices should be fixed, while asking players to report any remaining device-specific case. The Razer Tartarus and Swiftpoint solutions are independent older reports, so this page keeps them as fallback diagnostics.