Into The Breach is a fun, lightweight puzzle game disguised as a strategy game. The key to consistent victory is map control.
I've been replaying it recently since it is good to pick up and play to completion in one sitting.
I've stumbled into what has become my favorite overpowered custom squad:
Rocket Mech.
Smog Mech (immediately remove the nanofilter mending ability from the mech).
Jet Mech. I usually put Camila in this mech as my chosen pilot.
This squad outputs smoke from every mech, and thanks to the Smog Mech the smoke causes damage to enemies (but not friendlies). This allows for map control by smoking up and causing fire all over the board. Upgrades that allow for bonus smoke damage, more smoke output from the Smog Mech, and more smoke from the Jet Mech makes the damage per turn and map control insane. The only missions that cause any trouble are those where an unstable vek has to be kept alive or there is a limit on how many vek can be killed.
