I've run two Xeno (i.e., Aliens) battles solo today with about 10 humans and about 50 bugs (plus a few dinos as I started rolling high!).
The first game, 10 militia were trying to find out why a village had stopped transmitting. Their mission basically to search the four buildings on the table and withdraw. They searched three buildings in a row with nothing, then got three Xeno rolls in a row for something like 50 Xenos charging out of the darkness. The last three went down hard though, their backs to a wall, but in the end, no match for the numbers.
In the next game, ten soldiers came in for what seemed like a cakewalk. They breezed through the first batch of Xenos and it looked like they would do the same for the second, but one Xeno managed to make it into charge distance! This made a squad of soldiers Runaway, who sought refuge in a building-- occupied by 4 Xenos who immediately got a turn. Scratch squad one. The second squad tried to fall back, but couldn't generate enough firepower and got sliced up.