First, map resources (metal patches) were not depletable. So, the game would see massive economic growth as every metal patch would give resource indefinitely. Big econ ramp up, and a marked ability to come back due to non-exhausting resource patches.
The second characteristic is the flow-based economy that worked with build queuing. A player could queue up as many units or structures to be built as desired, as opposed to "buy and build" where you must currently have the resources necessary to build something.
"Queue" may be an imprecise word here, as the player could, for example, have ten factories all attempting to produce a series of units simultaneously (and similarly, have a swam of engineer units all attempting to build a number of structures simultaneously). That is, it was simultaneous building that would consume resources on the fly as they came in that was the core of this model.
The flow economy model meant that a player tracked resource income and resource usage: kept positive, all the queued up units or structures could be built. Go into the negative, however, and the resource buffer would be eaten into and the player would see all currently-building units/structures slow down in their rate of build progress, awaiting resources to come in.
The last bit was disabled in SupCom 2, out of concern that newer players often bottomed out their economy and had a bad time. However, after fan outcry, the flow-model and infinite queuing was re-enabled as an option.
You could build more units and you could command larger groups of them compared to something like SC where you couldn't group more than 12 per hotkey. The sheer number of units you could crank out also had interesting strategic effects if, say, your opponent had a balanced defense but not quite enough flak cannons, say, to hold up to a giant swarm of air units. I remember having to worry more about the specifics of what they were building than in games where there was a unit cap that increased the relative value of fortifications and defensive structures.
Sequencing was great too. Tell your commander to build a factory, then another factory, then a solar plant, etc, with seemingly no queue size limit. Queue up dozens of things in each of those factories too. Etc.
It always felt less "clicks per minute" dominated because of these things for me - though I was not a high level player or anything, just playing for fun - while the industry went the opposite, way into the Micro side and turned into things like Warcraft 3 and then LoL.
(I forget the name of Cavedog's TA sequel set in a fantasy world, but even that, IIRC, backed away from the giant armies thing.)
[EDIT] Not mentioned on the BAR front page but also pioneered in TA was wreckage. Destroyed units left wreckage behind that had to be navigated around or fired upon to clear a path. Wreckage could also be scavenged to recover the material used to construct them, allowing the construction of more units. In the race to build enough infrastructure to overwhelm the enemy, this could be the difference between life and death.
Or, anti-air units used as ground defense and ground assault units :). In my TA days, I had plenty of cases where I saved my base by ordering AA bots to fire on the ground, counting on weaker but much further-flying missiles to accidentally collide with the attacking force.
Also, Commander's D-gun. That one was an exercise in aiming, but early-to-mid-game, one well-placed shot could cut the attacking force in half.
I also appreciated the little things - like the solar generators automatically closing down when hit, to protect themselves.
Or, dropship bombing - IIRC when a dropship gets shot down, it crashes with all its load, which can sometimes be pretty explosive.
Maybe I'll just stop now. I have a lot of good TA memories.
http://zero-k.info/Forum/Thread/1784?postID=189519#189519
Or maybe also this (BA?)/Spring one, dating back to the time when shields were invulnerable to plasma shots and deflecting them, featuring a shot being randomly diverted to hit a commander that was hiding in a bunch of buildings, wiping out half the base in the resulting death explosion !
https://www.youtube.com/watch?v=g5eBkn45Jo4&list=PLkuJSFWAxE...
The upshot of this is that it creates opportunities for prioritization (and opportunities for blowing past your income if you're not careful).
You also didn't have to pay up front when queuing things, like you say with the opportunity to blow past your income, so your cash flow was the counter-balancing production speed limiter, but not in a way where you had to be constantly watching that bank account dollar amount before clicking "build."
But the music was magnificent orchestral work. It was also so depressing [ https://youtu.be/ljDyp__ejco?t=995 ] that I decided to play the game without music after a while. It's gorgeous, but too emotive.
https://soundcloud.com/ryankrause94/sets/beyond-all-reason-f...