You need to OB the area directly north of LZ-2 as a bit north of it, the Comms unit tends to spawn. The problem is if you do not OB or breacher it, its full of 2x2 and 2x3 hallways xenos can exploit as natural choke points and we know how badly the average unga does, combat wise, in natural chokes.
The 2nd OB needs to hit central / north hospital so you take out a part of Admin and have a straight line into Sensors, OR if you bypass that with breachers / go west and have some decent CT’s, you can use the 2nd OB to either wipe out Security (to stop the xeno counter) or OB right into reactors south which creates a open playing ground.
Unfortunately, OB’s are completely RNG, so unless you get a lucky comms unit north LZ-2 roll and either double HE, double Cluster, or HE + Cluster, there’s no point going LZ-2 considering the average skill level of marines. They will get lost and/or walk into chokes and die going LZ-2.
This is assuming that the xenos have an average skill level equal to your marine team.
Main 2 Routes:
Circles are OB points.
This route requires incredibly good marines to pull off since OB’s need to be done well, marines need to stick together since you move through quite a few chokes, breachers need to be utilized, in general its a high skill route. Not recommended for 90% of rounds since marines suck.
This second route requires a lot less skill and is simple. You only use one OB to clear admin / hospital (preferably cluster) because you want to prevent an encirclement from the West. The comms unit usually spawns north of LZ-2 in that one spot where the red line ends near south hospital and the squad that stays there will also intercept xeno hive if they try to encircle, while the rest of the marines push for Sensors and later Reactor.
You can save 2nd OB for Security to stop a good hive from contesting your rear OR if they suck you use it to blast past the choke SE Reactors to get right into Reactors.
These are really the only viable plans that account for xenos not being dumb; you can try a plan that rushes middle Reactor like Hunter Stafford’s plans but the problem is they are all or nothing since if xenos are smart they will flank behind and abuse your corpsmen / comms and cut off your retreat to FOB. Then its GG.