Mass Effect 3: War Assets and EMS
Mass Effect 3 is all about the war between the Reapers and the rest of the galaxy. Can mankind survive against a bunch of metal space-squids with vague and ominous names?
Basically, your effective military strength and war readiness are numerical measures of the strength of your fight against the reaper. Every agent that you recruit or resource that you capture increases the chances of humanity surviving the war.
War Assets: All the assets that you have acquired. This is represented by a number that, by the end of the game, will be in the thousands.
Readiness Rating: A rating of how "ready" different sectors are, expressed as a percentage. The default percentage is 50.
Effective Military Strength (EMS): Your "Final" score, and the number that will effect which ending you get. War Assets x Readiness Rating=EMS
What happens if you suck
Here are the different available endings, as determined by your final EMS.
0-1749: Everyone dies, and you are terrible.
1750-2049: Make one choice, everyone dies and Earth is destroyed. Make another, your squadmates survive and Earth is merely extremely devastated! Shepard is still toast. You'll notice this becoming a trend.
2050-2349: Earth is devastated, your squadmates survive, Shepard dies.
2350-2649: Make one choice, and Earth is totally saved. Make another and it is merely devastated. Either way, your squadmates live and you die.
2650-3999: Earth is saved, your squadmates live, and Shepard dies.
4000+: Make the right choice, and you get the best possible ending: Earth survives, your squadmates survive, and Shepard lives. Make the wrong choice, and Shepard still dies. Dying is sort of Shepard's thing.
Increasing your War Assets
The majority of the war assets you gain are going to be during missions. The more allies you gain, the higher your score. And remember that your decisions matter massively. If you let the Quarians wipe out the Geth, for example, you'll gain the Quarian armada, but lose the Geth's daunting techno-fleet.
You can also gain war assets by exploring sectors. By scanning, you can find war assets just hanging out in space.
Basically, complete every mission, and make the (potentially cold-hearted) decisions that will lead to your victory. Scan every sector. Scrape up every last ally you can.
There are more assets in ME3's DLC
Increasing your Readiness Rating
Your readiness rating can only be increased via points gained in multiplayer. So, have fun in multiplayer, and lots of it.