Tried it against AI on lost temple, seems like it could be fun. I don't know how balanced you want it to be, but some suggestions...
- The marine upgrade that adds 2 range and increases attack speed is way overkill, especially since you added ground medics. It pretty much makes them uncounterable by anything that isn't massive splash.
- Firebats are pretty terrible units in their sc2 incarnation even with the flame upgrade you added, you might want to make them a bit better if they can replace mauraders.
- Adding the hive mind emulators is pretty extreme, especially with the same stats/cost as campaign. It's pretty much an autowin versus zerg since you can turtle and take all their units. I'd either remove them, make the build limit 1, or something.
- You might want to limit the protoss monolith things to 1 also, or else you can spam them and creep towards the enemy base. There really aren't any zerg units with high enough health to take them out especially when they are guarded.
- Scouts are pretty awful compared to phoenix for their cost, about as terrible as they were in brood war. You might want to make them slightly cheaper or something idk.
- The melee infested terran costs like 50 25 but is worse than a zergling, the infested marine only costs 50 mins and is much better.
- The capital ship from the same tech path as the monolith is pretty ridiculous, void prism or whatever. It has the same cost/tech requirement as a carrier but has like 10 speed, more dps, doesn't require you to buy interceptors, has no build limit, and its ability is essentially a no energy seeker missile with a 20 second cooldown. Just one of these is way better than the hybrid hero unit.
- The dominion tech path didn't seem good enough to warrant costing 200/200 when the others are all free.
- Irradiate from the science vessel costs 25 energy which is hilariously op against zerg. It costed 75 in brood war but with how units stack in sc2 125 would probably be a better cost.
- The zerg cannon from the leviathon tree that attacks both air and ground seems like a little much, especially its range.
Also some bugs, you might already be aware of most of them but just in case..
- The tech tree with improved upgrades for terran is bugged and air armor doesn't work.
- When I went the purifier tech route as protoss the air upgrades were bugged and I couldn't get past 2/2.
- The purifier has the invulnerability buff from campaign before you destroy the nexuses.
- All of the hero units and a lot of the added units like mercenaries aren't affected by upgrades, this might be intended don't know.
- The parasite ability on the infestor replacer doesn't work
-It seems you can build multiple leviathans (and purifiers too i think), which I doubt is intended. I know you already said the leviathan wasn't finished but I'd recommend getting rid of the infispawning mutas and BLs lol.
- The refineries are red even if they aren't empty, still work fine though.
Only played for like 2 hours mostly terran that's about all I can think of. Cool concept though better than most of the other garbage on Bnet.