TLDR; This game is fantastic and has a lot of promise. Right now its a 7/10 but with some polish can hit a 10/10 easily.
So most of the "issues" i talk about below are resolved the moment you get to Torment 1, which is kind of like difficulty. More like a new game plus.
New Score 8/10. Keep polishing my dudes!
Boarding
I agree with the other comments that Boarding is the most effective strategy, that also has the least amount of effort. Similar to the Stealth Archer build in skyrim. You can do it accidentally. Most situations are just easier to handle with boarding which most ships are able to do out the gate.
I think disabling the "recall crew" teleport back and requiring your crew to exit via the death sleds (loading them up then launching them back) would encourage boarding maneuvers with more expendable units. When they leave they should cause a breach. It would also make risking your valuable units/gear more interesting. Firing an empty sled at a more useful access point for an escape could be an interesting strategy.
The above would also increase the usefulness of teleporter tools. Perhaps a dedicated system for recalling units via teleport would help? It takes power, can be damaged, needs to be purchased, picks up 1-4 random allies in a room depending on upgrade level and power, etc etc.
Similarly, summoning minions (like thralls and undead) directly on the enemy vessel feels less cool than cramming them into a death sled and ramming it into the enemy. OBV this is a big nerf so if implemented I would expect some kind of charge or cooldown change.
While we are at it, make death sleds consume munitions and travel just a bit slower.
I really love boarding, but I think it needs a nerf.
Modules
I think the faction members (blood cultists, death cultists, tech priests) should hand down their type to their summons/minions (thralls, ghouls, and husks) for the purpose of these modules. I would never expect a tech priest to outfit their husks with armor without first slapping some on themselves.
Commanders should probably have a type so they can benefit from some of these.
I love finding any module that isn't related to unit health (see boarding). They are so rare, it seems I only find them during events. I can't recall ever seeing one in a shop. This exacerbates the boarding issue above.
Psyker Support
A system or room that decreases psyker cooldown times while powered could be fun. A ritual room? Perhaps it needs to be customized to the psyker types, so a blood cultists can't benefit from a ritual room configured for the death cult?
I am not sure if I just haven't bumped into them during any of my runs, but a psyker that has two psykic slots would be interesting. Some spells you want available but don't need all the time. Being able to cast while the other is on cooldown would be very powerful however. Perhaps the cooldowns don't tick while channeling?
Necromancer's not being able to have new psychic powers assigned feels odd. I see the utility in having a psyker with a tool slot but it feels more like a mistake than a feature.
BUGS and quality stuff
When i drag a ship weapon, unit weapon, or tool from inventory onto an occupied slot, I expect them to swap places. Game crashed instead. (The auto save feature was great, only lost like 30 seconds of time.)
Temp units like subhusks and summonable units can piggy back to later nodes in the death sled. I initially thought that I was cheesing the system, but then they die as soon as they exit. So they just kind of took up space in there and prevented me from loading it with "real" units. I would prefer not to micro manage this.
When the deathsled is damaged, the units over its new cap die. I think this is fine, but seeing them pop out and die would be some nice feedback to know that it is happening.
Animations
Love the warping animation. The portal looks so sleek! I with it was also used when you appeared at the next node instead of the zoom animation.
Many little animations are great! The psyker effects I have seen are great! I love the way the missiles pop out then start flying. Air flow for breaches and open doors looks great. UI is the perfect mix of usable and dystopian. Feels cluttered at first, but feels immersive shortly after.
Fantastic game! Keep up the good work.