SimAnt had an oft overlooked secret. If you burrowed down as far as you could go in your home nest (which took a good number of minutes,) through the darker earth and into clay, and finally off the last screen, you would suddenly find yourself at the bottom of a random enemy's nest! With this trick, war could be waged on two fronts, top down and bottom up.
I have only verified this on the Amiga version, however. (qousqous reports this also works on the Mac version.)