Sounds like Eve Online.
From Wikipedia:
"On March 15, 2009, Eve Online achieved a new record for the maximum number of simultaneous pilots online with 53,850 concurrent accounts logged on to the same server."
I don't imagine MS will have too much trouble beating a little-known Icelandic developer.

"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.







