> One could actually have, for example, an artillery projectile in mid-flight accidentally collide with an aircraft.

Or, anti-air units used as ground defense and ground assault units :). In my TA days, I had plenty of cases where I saved my base by ordering AA bots to fire on the ground, counting on weaker but much further-flying missiles to accidentally collide with the attacking force.

Also, Commander's D-gun. That one was an exercise in aiming, but early-to-mid-game, one well-placed shot could cut the attacking force in half.

I also appreciated the little things - like the solar generators automatically closing down when hit, to protect themselves.

Or, dropship bombing - IIRC when a dropship gets shot down, it crashes with all its load, which can sometimes be pretty explosive.

Maybe I'll just stop now. I have a lot of good TA memories.