To get the "Smash Brothers" achievement, you need to get two adjacent, fully-charged Compressors to fire at the same time. I haven't been able to do this. Is there some setup that makes it easier for two adjacent Compressors to fire simultaneously?
Things I've tried: (c is compressor, C is big compressor, . is a path, x is a wall.)
1) A bunch of Compressors in a row, and hoping against hope.
c.x c.x c.x c.x
2) A big compressor behind a small compressor, so their blast areas overlap and start at about the same place.
3) Putting two compressors right next to the virus-entry place. (E = entry)