They did some neat game mechanic tweaks, especially of the previously useless units: mechanics and thieves being able to revive and capture vehicles. Keeps the spirit of the old game but makes it more fun.
I now see what the creators did there. I didn't think about it when I was a kid.
The nuke truck was made the Ukrainian unique unit only in OpenRA.
Original RA had a tendency to devolve into tank spamming. That takes skill. But it's closer to tactical than strategic. Does OpenRA deal with this in any way?