The reason I thought that that number was interesting is because you can do a little math to speculate as to how many major events in the game will actually influence the ending. Lets break down the numbers really quickly. The way you figure out the total number of combinations possible in a given situation is to multiply the number of outcomes in each situation by the number of outcomes in the next, and so on. For example, if you had three major events which each had two possible outcomes, the total number of endings from all of those events would be 2^3, or 2×2×2 = 8.
If you take Pete’s comment of 500+ endings, round it down to 500, and do some simple math, you get 2^x=500. If you solve for x, that gives you x=9 (roughly– 2^9 is actually 512). So if Fallout 3 has nine major game events which have two possible outcomes for the end of the game, that would put us at just over 500 possible endings… exactly where Pete claims the game is. Now, that assumes that every scenario has exactly two possible end-game outcomes. If he’s including endings where you don’t encounter some of those events (so that ABA and ABAA would count as two distinct endings), or if any of those major game events have three possible end-game scenarios, we’re looking at even fewer actual important events in the game that can influence the end– possibly as few as 6 or 7.
There’s more, interesting read, all the best to Cameron now the he is starting a new cycle in his life.