Btw, here is something you might have thought about, idk:
Units like Engineers or something that could capture buildings, maybe a kind of Infiltrator unit? Capturing buildings and even stealing resources from the enemy could be fun to see, and being on warcraft engine, it could contribute to the feeling of two worlds merging.
Also, tesla technology! There's got to be room for a Tesla Coil building!
Although loghtning sounds in wc3 are weird imo, maybe copy the sounds from RA2/3?
Not sure if Chrono technology would be included, as it's the source of all problems storywise.
Do you plan to make units recieve veterancy levels? It would be great of course, but I can't imagine how it can be realized and if, how much work would be spent on creating this mechanic, maybe better to leave it for now?
Was thinking about air units from c&c, not sure how airplanes would look in wc3, helicopters though could be good?
Edit
Global powers for every faction or just the C&C ones? I can imagine a button on a Town Hall, when pressed would show some powers with a long cooldown. Maybe a triggers can be made, counting kills and unlocking those powers..
Superweapons - right now I think it would be weird to have them, considering in wc3 maps are smaller and not much space is available for base building, if this has a place here. Faction powers are a streched thing too..
I'm not sure how you feel about resources; there are Gold, Lumber, Ore, Tiberium.. Seems overwhelming.
I'm trying to imagine high-tech armies suddenly appearing in, let's say, Ashenvale forrest. Will they establish some kind of city and have an industry to produce their stuff?
What if Undead appear in Washington and start rampaging, later fighting the police, army etc; how will they fuel their war efforts if there is no gold available to mine? And what about other races..
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These are some of my random thoughts. Some ideas MIGHT prove useful, most probably won't xD
Repeats they say could destroy a whole planet with just one spaceship...
Soviet due to Tesla and Kirovs