Built game doesnt work on other computer?

The built game works on the computer with unity, but when I go to another computer and try to launch exe file, it says mono failed to load dll or something like that. Do I need to includbies exe?

You only need to copy the .exe and the data folder (and keep them relative to each other). Did you have extra files that need to be included, like DLL’s or other files that the runtime might need? If so, make sure those get copied too.