Stratosphere had nice ramming mechanics back in the day, you could stick spikes on your fortress and if you rammed those into exposed systems they did massive damage, on the other hand if you hit a wall (fortress equivalent of heavy armor) your spikes would get blunted long before the wall goes down. If you were particularly crazy you could just ram your fortress's exposed structures into the enemy and simply hope that yours had more HP left than his. Also if you destroyed the core of a fort it would explode and rip a chunk out of you if you were in melee. You could even get giant drills but I think you couldn't ram too hard with those or they'd break, you'd have to hover in drill range of the enemy for a while which is why I never bothered with them (spikes, wall and boosters! Who needs sanity?).