MMM1 is a series of monocolour matches, where a pair of players plays lots of games in a single monocolour matchup, to find out how balanced it is. It’s been inactive for a while, but FrozenStorm’s trying to get it going again.
Incidentally, @FrozenStorm, the main series thread might get more attention if it has the #codex:codex-play-by-forum tag removed, since threads with that tag don’t appear on the main forum page.