Ok, so blocking is really annoying; we've all been killed because a teammate was in the way. So it needs to be reduced.
I was thinking about the relative sizes of the aliens today. Dretches could fit under pretty much every alien except for the basilisk, and the basi could fit under everything except the dretch and the mara. Unfortunately, hitboxes cannot be changed to accommodate this, as discussed in http://unvanquished.net/forum/showthrea ... ward-Slide. So what if dretches and basis could pass straight thought rants and the like? It would prevent a lot of block. One thing I can see being a problem, is basis healing goons and rants from inside them, thus keeping themselves safe, and getting some armor as well. Another is that a rant might become a barricade, and let swarms of dretches attack the enemy, then retreating to behind the rant to heal.
I'd say the easiest method is to prevent collisions between dretches and rants.
But i like your idea,though i dont really agree with marauder on top of dretch, marauders are fast enough to jump over with ease and their dodging abilities, i dont think i ever heared about anyone complaining about dretch blocking mara my whole time ive played trem with an exception of vents.
Ignoring collision altogether is not really a good way to avoid blocking. You even proved this in your own post.
Not to mention it will look broken.
What we could do, though is either encouraging players to use wallwalk more (which they, honestly speaking, don't use to its full extent) or implement some sort of momentary burrowing that won't conceal the player enough to let him remain invisible, but will get his bbox out of the way of others.
Burrowing ability limited by amount of time spent burrowed could be interesting as well both for timed ambushes and preventing «burrowcamp».
I think I've seen the burrowing idea mentioned here already, by the way…
I've no idea.
Okay, perhaps I do. Perhaps it'd leave a visible hole in the ground where the alien is burrowed.
What would it look like in some of the space station maps? And what if there's a room directly below the one where the alien burrows? We already have this problem with dead things sinking into the ground. (Dretches floating in midair are not a feature).
