I'm glad to see Finaly somebody would make Alien Swarm mod For blockland Anyway
First of all the Queen was made as unused Alien but its a good idea with make it
Second you missing the Eggs where the parasites comming from
http://alienswarm.wikia.com/wiki/EggI think this Should NOT be made to ZAPT , caused by the following things such as, brick damage (they would basically Break anything except baseplates or cubes, which they dont even break the walls or things like that in alien swarm) And if its ZAPT it would be more like Survival than campaign itself (which is not fun at all with just survival nonstop)
i would more prefer Left 4 Block / zombie mode, since it have better gameplay and you can turn off the brick damage for zombies
That is my option