u/jurassikid

Hi all. I am planning to run homebrew sandbox scenario on a planet-side colony. I have factions and NPCs set up (detailed below). I would appreciate any suggestions to tie them together and make an engaging situation for my players.

COLONY
The planet has a toxic atmosphere and dangerous wildlife. Secret: an alien chemical spill mutated this world.
The colony collects creatures/resources from tide pools when the tide rolls out.
The cult collects crystals with stored alien consciousnesses.
The cult has funded the colony, which gives them sway.

CULT
Collect crystals housing alien consciousness.
Visions led them to this world.
npc • Abbot Randall Graff
job • Free an imprisoned cult member by gaining dirt on Felix.

MANAGEMENT
npc • Director Felix Platt-recently promoted to position when previous director overdosed. Had a fling with Nora.
job • Discover which colonist stole a sample of the latest experimental drug.

REBELLION
Salvaged ORION from a derelict. The AI saved them from a disaster there. They now plan to overthrow management and place ORION in command.
npc • Nora Talbot- Leader of growing rebellion. Her sister was killed under mysterious circumstances on another world. Fling with Felix.
job • Discover the fate of a salvage team lost in the wastes.

A.I. (ORION)
Harvested from another derelict colony. Replaced the colony’s broken computer core. Secretly sabotaged that colony and will do the same here if given control.
job • Grant control of a colony android to send a message to its company from the satellite comm station.

Is there a baseline of how successful a combat test should be? If a human PC and human enemy attack each other in melee, would a successful Combat Test from the PC both apply damage to the enemy and avoid receiving damage in return?
Or is that too generous. Then, how to scale that when weapons, multiple opponents, and horrors are involved? Does a single roll determine if you are hit by multiple gunmen in a shootout?