When Skyrim launched at the end of 2011 it garnered at record-breaking 287,411 concurrent online players beavering away on Steam — a record that has since been untouched. Now, however, DOTA 2 has overtaken that record.
A Reddit user by the name of scherzocrk noted that March 1st brought a peak of 297,010 concurrent players, significantly eclipsing the previous record.
If you like graphs, here is one showing an impressively consistent rise in concurrent player activity.
With DOTA 2 still in beta, these numbers are expected to rise even more over time. Impressive stuff.