Make more special buildings for unlocking units and powerfull units, other buildings, more powerfull defences along with allready exsisting defences and superweapons. Etc etc.
Old C&C/Red Alert wasnt fast phased really. And there were lots of buildings to build to unlock other buildings and units. Ontop of some having special abilities. Like extra strong cannons or full map view(Meaning no fog of war after the thing is build) etc etc. There was also special powerfull units in kinda all of the games. Tanja and Boris as an example.

All the old Red Alert and C&C games where kinda slow/Medium phased.
Where 8-Bit Armies is really fast phased. More like Starcraft fast phased. Sadly.

Speed option and/or what i suggested above. Would really help make the game much more like the old C&C games, which you like to mention it should remind us of.
Specially in term of how fast things are allready going.

As i see it right now. 8-Bit Armies is a rush game. Build fast and attack. Have fun. If you like that type of game.
Only thing that reminds of C&C is the base building parts with power and so on. But its not very much. Sadly.