wiki page for reference
Goals:
Make Hivemind more fun. Cut out the things that made old hivemind unfun. Mindshields are no longer a one-shot complete answer to hiveminds existing, though they do help. Make their power of gaining process faster. Remove incentives for silent play(just running around and using assimilate on people). Remove mindshields hard-countering them. Make objectives more interesting and have them incentivize and give ideas for active play.
Give Hivemind its own niche. Focus on mental manipulation, tricking the crew into doing what he wants them to do, empowering or crippling crewmembers and other antagonists, and accomplishing their own objectives. They should be a puppet master and a diplomat. Find the other antags, work with them to get both your objectives done, and escape alive.
Non-goals:
Make it a team antagonist. This was part of the problem with original Hivemind; the strength given by numbers was too enticing, and a lot of hiveminds leaned too hard into doing nothing besides assimilating people because of it.
Make it a solo-murderbone antag. We already have a Wizard and a Changeling. A hivemind should not be conjuring some mysterious, overpowered wizard weapon or suddenly having a sword for an arm, though they should be perfectly capable of debilitating lone targets for a fight, and running away if they're outmatched. If they're getting directly involved in a conflict, they're either fighting another hivemind or something has gone extremely wrong.
It should be somewhere between the two; not completely self-reliant, not completely reliant on its temporary allies.
Make the hivemind completely invisible. There should be at least one way to find them, even if they're mostly casting abilities through other people.
Roundstart abilities:
Hive Sight: Important change; you can cast your abilities through people using Hive Sight. This makes them less directly visible once they have a few vessels.
Assimilate: Casts much faster regardless of distance. This was part of the problem that caused them to take too long to actually do anything fun.
Telekinetic Hand: functions like pink, activated telekinesis instead of weird ranged unarmed combat.
Add Network Invasion, Psychoreception, and Reclaim here; offense against other hiveminds should be encouraged by making it available to all of them at the start of the round. They already take up each other's space by assimilating the same vessels, so they will be itching to take each other out.
Add Telepathy. It's a fun and flavorful ability, and it makes no sense for a hivemind to not have it.
Tier 1:
New abilities: Sunder Mind: directly gives the target a decent amount of brain damage. It should be lethal in 4 casts, but cooldown quickly. Deals less damage if cast remotely; lethal in 12 casts in that case.
Adrenaline Surge: boosts the target's movement speed and stamina damage resistance. Adrenaline Surge is useful because of the aforementioned Hive Sight change, and you can affect yourself.
Move Induce Panic here. Its replacement is more permanently debilitating, so it can work as a tier 1 ability. It provides options; while not being objectively worse or better than the other, because you don't always want to inflict traumas on a person.
Tier 2:
Telekinetic Field and Repair Protocol are fine as-is, I think. Only change is that if cast remotely, they benefit the vessel they were cast through. Like they can walk through the forcewall, or they get healed instead of you.
Put Bruteforce here. It provides counterplay for the counterplay so that the antagonist can still function if they were exposed early. The stun is complete shit, though. Instead, bruteforce assimilate should take longer and potentially out the hivemind in some way, making them easier to find if mindshields have been distributed. Maybe their eyes glow pink, or something.
Tier 3:
New ability: Induce Psychosis. Lets you choose one trauma from the full list of mental traumas. You get to choose the prefix(If you don't, it's assumed to be basic). The more specific and mean you are, the longer the ability goes on cooldown. Using this on assimilated crew lets you pick from special traumas. Cannot be used on yourself, cannot be used to make permanent traumas, cannot be used to hypnotize.
Chaos Induction can be used as many times as you want, on a very long cooldown. Instead of hitting four vessels, it hits two of your choice up to four at once, allowing you to give different people different objectives. If you hit the same person, it changes their objective instead of adding more. This could be seen as conflicting with non-goal 1, but the lengthy cooldown makes it less of a team antagonist and more of an underling-creating antagonist like hypnoflash Traitor and flesh Heretic. Plus, this allows for true 'unseen puppet master' gameplay where you just give people objectives and guide/manipulate them without ever telling them your actual name.
Mind Control caused a lot of administrative problems IIRC and was nerfed into the dust as a result, but I still like it as an ability. As with Hive Sight, you can cast your spells through a Mind Controlled target.
Tier 4:
One Mind needs to go, mostly because of the earlier changes to Assimilate. I feel like making Assimilate faster would make One Mind happen much earlier in the round. Plus, it would encourage a completely silent "I only ever assimilate people" playstyle, which is exactly what we don't want.
New Ability: Mind Shift, letting the Hivemind swap bodies with one of their vessels. This would happen in stages; first, the hivemind's head pops like a grape. Second, the target gets a message about a headache. Third, after about a minute, the vessel briefly passes out and the hivemind becomes a split personality of the vessel. Fourth, after a few swaps in control, the hivemind eventually takes over the body of the person they shifted into.
They can still cast spells during Mind Shift after stage three. Mind Shift can be countered with a mindshield before stage three, forcing the hivemind to stay in its brain(for forceborging). After stage three, it requires a lobotomy.
New Objectives:
Hivemind's current goals are boring. Syndicate affiliation is overused.
Instead, Hiveminds are working with the space wizards.
The wizards want to study their mysterious power to see if they can learn it for themselves, and send them out to accomplish various tasks on NT stations, giving them random access to classic objectives like 'steal the antique laser gun'.
Could receive open-ended objectives like the Revenant's "torment the clown", if only to give them ideas.
Finally, could have an objective to investigate a specific location where psychic energy is located and absorb that energy. A large amount of psychic residue(see next section) is left in the location. This special residue can be assimilated(it takes longer, melee range required), doing so completes the objective and gives the hivemind a few extra vessels for the purpose of unlocking their abilities. It cannot be cleaned. Could have it also give them corporate secrets as flavor, i.e. this is where NT had a previous hivemind killed to keep them from doing something against the company.
Other Changes:
Most hivemind abilities will leave psychic residue behind at the hivemind's location. If cast through a puppet, the residue is left at the puppet's location at time of cast AND the hivemind's location. This cannot be seen by non-hiveminds except with Psychometric Scanner Goggles(new Psychologist item?? could go to the detective, but he already has Heretics and Traitors to deal with. + gives the psychologist job content) which also allow you to see someone's mood on-examine.
Examining residue with the scanner goggles gives you a pinpointer to different locations based on how the ability was cast; if it was cast through a vessel, it points you to where the hivemind was standing when the spell was cast. If it was cast directly, it gives you a fragment of the caster's (undisguised) name; A letter and what position it goes in. It's sort of like a mental fingerprint, without adding an entirely new database for mental fingerprints. Residue can be cleaned by spraying neurine on it.
The idea that mindshields completely shut hiveminds off is awful. It's too easy to get them in large quantities for this to work, and makes it so any other hivemind going loud punishes all of them. Instead, I suggest that it doesn't remove assimilation, just protects against it. Instead of making someone completely immune to the hivemind's other abilities, it reduces their effects. Shielded targets take less brain damage from Sunder Mind, only give you sight OR hearing with Mind Sight, et cetera.