They aren’t in the game yet, so they don’t necessarily need to be clearly defined. Especially since as you say, it presents a big of a game design challenge the way they are currently described.
I agree with Ingvar that they don’t necessary have to be mobile. Make them tethered to a certain point that doesn’t have a beacon area. Come up with reasons for why they would appear on the planet. Maybe they’re alien visitors that appear and will siphon the energy from the planet, create a literal vacuum of magma that they consume. If not killed in a certain amount of time, they eventually fly back up into space and disappear.
This, to me, sounds like it could be an incredibly fun aspect to the battle. If it were easy, it wouldn’t really be epic. The thought of getting flung off of a titan is exciting to me. You have to have some risk and sense of danger in a game, otherwise it’ll just be a cake walk.
I don’t think so. They advertise the game to feature titans, so doing otherwise would be costly imo. Granted, I was more excited about PvE aspects to this game than I was building, although I do like the building already. From what I’ve seen, they should really be fleshing out the PvE in this game more as the building is already really good.