Tunnels — Meat Hell

Maps get a second deck. Units fight through tunnels under the rock and cross bridges over it. New infantry models, and a sniper.

Tunnels and bridges: units walk, fight and swim under the rock. The roof cuts away round your selection so you can see them.
Tunnels are dark: lamps, things hanging from the roof, and headlamps on your units. Gunfire under the rock sounds muffled.
A sphincter can seal a tunnel mouth shut, crushing anything caught in it.
The AI uses tunnels to sneak, and guards the mouths into its base.
New 3v3 map Gullet Isle: an island split by a mountain, fought through its tunnels. Sugarloaf and Koko Head get tunnels too.
Bridge kits in concrete, blue rock and meat. Some tunnels are lined with intestine.
First person gets mouse look, sprint and jump, and small infantry can walk along walls.
The Raw Chicken was rebuilt: it trots on all fours, and unloads by rearing up and dropping its passengers out of its bottom.
New infantry models built from butcher's cuts: the Meat Zombie, the Spitter (it spits teeth from the hole where its head was), the Bone Launcher (its forearm is the cannon) and Patient Zero (a glowing heart under a cape).
New unit, the Eyestalk: a sniper with a ribcage crossbow. Beyond its own sight it shoots whatever your other units can see.
Infantry stop skating: new walks matched to their speed, feet planted.
The AI recovers when its Construction Yard dies, and pulls back from an attack that has gone badly.
Multiplayer matches start together once everyone has loaded. The loading screen shows tips.
Placing a building hatches the ground where it can go. Walls and towers no longer stretch your build range.
Edge-scroll zone and scroll speed in Settings. Repair starts without credits and waits for them.
New ground textures, shore foam that looks like foam, and a proper wake behind swimmers.