If the mouse cursor is invisible when running Tiny Glade, it's usually due to video capture software interfering with the game.
If you use an app called Medal, please refer to its own troubleshooting page.
If the cursor is invisible while streaming/recording with OBS, try changing the screen capture method. Reportedly, the "Windows 10 (1903 and up)" method can cause this issue.
Some players experience this problem if they have "Display pointer trails" enabled in the Control Panel, and Microsoft Insider / preview versions of Windows are also known to be problematic.
Windows HDR mode might also be the culprit.
If everything else fails, change Tiny Glade to windowed mode via Alt-Enter or F11.
On Linux, it's probably Wayland-related; see here.