Ok so what exactly does Global readiness bulshit change? From what I can see I still had access to all three choices at the end.
If you mean 50% - 100%, it's just calculating your final EMS (effective military strength). If you're above 5000 then you should have access to all three endings and the 'best' of each of those. If you have 50% readiness and you have less than 5000, let's say you have an EMS of less than 1750, then Earth will be destroyed no matter what you do. The endings and the effect of EMS are chronicled by IGN here - http://www.ign.com/w...ffect-3/Endings
Frankly whoever wrote the endings needs to be taken out back and shot