All of them.

Well its definitely possible. But it would just be torture.

I'm just reluctant to believe a single person is playing on those accounts.

All of them is the answer. Look up how many 360 games there are and thats the answer. No one is going to have a handy count of all disc, downloadable, and expansions for games have been released.

Highest score of my friends is 200k and he manages to do his job and have a girlfriend. He has played 310 games.

Now I feel ashamed with my sub 50k GS... but in my defence, this is my second account!

my answer was to severance in that i should have said how many games when he said  all 360 games  ,and i mentioned me saying xbox rather than 360 because i thought he knew that and was being smart, if that is not the case i apologise to him .

you could have said  i don't know how many 360 games there are, as to dlc etc it was never mentioned.

It is relevant though as it adds more gamerscore than XBLA games which are also relevant to how many games he needs to beat. I don't really understand the mess you wrote there though so I can't respond to it. I am not trying to be mean but the sentence structure is such that there isn't any discernible message. I guess you are asking about original Xbox games? None of them have achievements to the best of my knowledge.

One gamer said he thought he had reached a cut-off when his 960th game didn't register on XBL.  It turned out to be a false alarm but there would be around a thousand by now.  Stallion must be independently wealthy to afford them all, plays all the quick and dirty games and never needs even a third playthrough.  Not a wrpg fan I take it.  Still that's an incredibly focused effort.

thats because the message wasn't  aimed at you

That is insane. I just recently reached my 15k milestone (I have 666 achievements. rofl). Though I only had the Xbox 360 for 19 months and I play on multiple platforms. If I had the Xbox 360 since launch and I played nothing but Xbox 360, it probably wouldn't be a stretch to think that my gamerscore would have been in the six digits.

But 500k? Thats 100k per year assuming he started around launch. Which would mean averaging 8,333 acheivement points per month. He'd have to complete the equivalent of 8 games in a single month! Now if every game was a easy 1000 like Avatar: The Last Airbender, that's not a problem at all. But that's not the case.

You don't need to be independently wealthy to be able to play 300 Xbox 360 games. Not when you can rent. But he definitely would need to be independently wealthy to find the freetime to rack up achievement points that quickly.