I've been working on a mod for gits and shiggles, and an looking to make a custom campaign around it. I've been thinking through the tech tree and wondering what you guys think or what's missing.
Stalker (Co-op one)
Dark Templar (co-op, but no void stasis)
Dark Archon (Brood War inspired has mind control, feedback maelstrom, made from DT)
Disruptor (Co-op version)
Oracle (modified LotV version, permanent revelation, pulsar beam is standard attack)
Scout (range upgrade, stun missile upgrade)
Void Ray (Requires Fleet Bacon)
I'm including the scout since the dark templar have their own versions of them, and moved the void ray to fleet beacon since there is a lot at the starport. I'm not sure what I could do to make it capital ship worthy though. The Oracle has permanent revelation for a mission idea I'm thinking of where you'll want to keep track of dropships attacking your base. The disruptor is meant to serve the role of Nova's drone for co-op, sneakily taking out buildings like missile turrets.
I'm looking putting emphasis on smart use of units like in Brood War over the mass all the things in SC2. (Yes I know that was a thing in BW too but it wasn't ideal due to controls).