Turrets

Machinegun
These rapid-fire guns are effective general purpose turrets. They can engage air and ground targets, and are also good at shooting down incoming rockets. However, they are weak against armor.

Steam charge: A long super-rapid-fire burst in a set narrow arc. It does not adjust as the target moves.

Upgrade choice:
 * Hornet
 * Locust

Cannon
These slow firing weapons are excellent at taking down armor. They can only shoot at ground targets, but they cause damage in an area of effect (AoE).

Steam charge: Fires a spread of shells at a set location.

Lightning
Often called Tesla in most games, these weapons shoot electricity. They can engage air and ground targets. They have both a chance to cause critical damage and a chance to stun, which slows targets significantly. Very effective against robots.

Steam charge: A powerful blast guaranteed to stun, if the target survives.

Upgrade choice:
 * Hurricane - Shots can chain to a larger number of enemies.
 * Tempest - Increased chance to shock enemies. Warning: For some reason (possibly a bug), damage from the Tempest does not count as "Lightning" damage. Enemies weak to Lightning damage do not take bonus damage from it.

Saw
Another slow firing, but hard hitting weapon, these shoot saw blades at enemies. The blades will pass through multiple targets. Some special enemies can shoot the blades down.

Steam charge: A more powerful shot.

Missile
The last turret unlocked.

Shotgun
This turret can not be unlocked, but is provided as a reward for defeating a special mission. The earliest it can be acquired is after the Cannon turret and before the Lightning turret.

Shotgun turrets are slow firing, but cause good damage, and are very effective against airborne targets. Visually, the shots consist of a large number of projectiles in a very narrow cone. They have slightly less range than other turret types, but not by much. Like Machinegun turrets, these are not great against armor.

Steam charge: A more powerful shot.