I love the idea of more content that makes sense as a bridge from starter tech to space age tech. This should fit somewhere between a gun turret, a tank, and railguns.
My other mod adds a heavier 3x3 version. https://mods.factorio.com/mod/heavy_cannon_turret

This is an edit of the Cannon Turret mods by VortiK, Ellswor, Kafoaai, Touhma, and Reckless and uses a mix of the assets and code from their mods.

8-way placeable like a railgun, so it is not able to be rotated after placement, but it's quickly minable

All configurable, but below are the defaults
cone of fire: 45°
range: 15-45
cooldown: 240 ticks
HP: 600

Changes color by player
Can hit and damage asteroids
Reworked tech to fit in naturally as a prerequisite for the tank.

Works best with mods like Balance Ammo Damage by Stargateur and Disable Cannon Shell Friendly Fire by FiveYellowMice so that these aren't overpowered and don't destroy you and your base.

I made this mainly for my own multiplayer games, but in an attempt to make it work for anyone, most of the stats are configurable.
Original: https://forums.factorio.com/viewtopic.php?t=14957