I'll categorize this as BYU Football since most are wanting rooms at in Las Vegas for the Game and the linked thread was concerning football. Hope that's ok.
It's pretty straight forward. MGM has some slot games on your phone or computer. They are free to play. You basically win Gold Loyalty Points and then you can redeem them for prizes. The most expensive prizes are free rooms, but they also have less expensive rewards, such as a free drinks or something. There are 5 games and you need to link them up using the same email address so all your progress will be saved and combined. The games are called myVegas, myKonami, Pop! Slots, myVegas Blackjack, and myVegas Bingo. There is also a Facebook game. I find it much easier to link everything up through Facebook. Once you have them all set up, you can play them and earn the Gold LP.
There is another way where you don't even have to play to earn them though. This won't work on iPhone or on facebook. If you have an Android you play open the games up and just let them sit. Those earn LP over time rather than playing. If you don't have an android, on your computer, you can download BlueStacks. It's basically an Android emulator. From here you can play the Android versions of the games on your computer. Do the same as before and just turn the games on and let them sit. You can earn about 20,000 LP per day. 1 night at the Bellagio is 125,000 LP and Aria is 150,000. All others will be cheaper.
Once you have have the amount of LP you need to stay at a hotel you want, you simple redeem it, the room will go down as a comped room, and all you have to pay is the resort fee. I've done it before and it's pretty straight forward. It just take a little time to build enough LP.
Here is the link off MGM's website if you want to look into it more.