hit the screencap button a bit late, but it still shows the portrait awarded from the achievement.
win an 8 player FFA with 7 insane computers. not really hard if you cheese it.
play terran on lava flow. immediately put 5 scv's in command center and float it off to one of the island expansions. the island expansions both have two expos on there. from there saturate all of your gas/minerals asap, macro as much battlecruisers as your supply cap can handle, you should have plenty of minerals, MAKE ENOUGH TURRETS TO BLOCK OUT THE SUN, not mandatory but nice to feel safe. wait till theres one ai left, steamroll his black ass with bc's, win. if you are afraid you might fuck up, attempt taking the other island, though, make turrets asap or bring your bc fleet to defend. i kind of fucked up and failed to get the second island, but it didn't matter.
all 7 computers were set to random because i didn't really see the point in setting them otherwise.
you can obviously do this on other maps with other races, but if you want the achievement without putting much effort, that's an easy way to do it.