Ha, seems that you guys dont know anything about cracking and how they beat protections. UPX is useless. It only packs your exe, it does not protect.
UPX can be unpacked with 1 minute, even less.
If u want serious protector then purchase Execryptor or Armadillo, use maximum protection that they give. ASPR: crc check, debugger check, time changing etc, ARMA: copymem, nanomites, anything it gives to you. Also try to use FindWindow API to find cheating tools windows by its name etc. Also game hacking tools. Like "Trainer creation kit" etc. If this window is active then kill this window or just dont load game. Do not display messageboxes like: Game cheating program is active, Please close it before running game". By these messages, the cheating tool check can be busted with changing one byte.
Need more inf? Just ask me.

Remember! There is no BEST protector!! EVERYTHING is crackable but with my tips u can make it harder!