Depends. If the developer uses modern recommended practices there should be both x86 (for Windows 10 and Xbox One) and ARM (for Windows Phone 10) releases in the app store. If they are some back-water mobile game developer then chances are they will only release an Arm version of the app targeting Windows Phone 10.
You cannot natively run the Windows Phone 10 version on normal x86 based Windows 10 because of the differences with the executable instruction set. One can in theory emulate it, but even with powerful computers there is a good chance of terrible performance so emulation is usually intended for developers/debugging. If the app is to run on x86 Windows 10 the developer needs to release a build of it targeting x86, which is the recommended practice for modern Windows apps.