Best anime this season. Muv-Luv Alternative Total Eclipse.

The last and the biggest Strain of BETA is the Fortress class. While they don't pose many threats to TSF, when lots of them shows up the battle won't be going well. The fort class can easily destroy TSF with their legs or with its stinger which secretes strong acid enough to kill a human. Probably their main role is to be meatshield protecting the Laser class as they are hard to kill and they can also carry several small BETA strains inside them. 120mm will work against them though melee is possible considering the main protagonist of Alternative killed more than 20 of this train under several minutes mainly with his type 74 longsword while a Squad a hardtime already facing one of this class.

BETAs are pretty much mindless creatures which receive order from the Hive. Out of many hive there is a leader of the BETA which resides in the Kashgar Hive. This BETA strain is known as primary objective which is probably the main villain in alternative and Human will never really win the fight against BETA unless they kill this guy. The primary objective command all of the hive and provide strategy to the other hives based on the information given to it. The main protagonist manage to destroy the primary objective which give a hope to humanity at cost of losing people precious to him.