For those who expect troff to be an ancient relic, Neatroff and Heirloom troff include modern features like microtypography. troff is still great for a lot of applications.

My needs are pretty simple - a program that makes grocery lists that I print. groff with the ms macros works very well. I used to use LaTeX but never figured out how to use it without installing gigabytes of stuff. This is my fault - surely I could have learned plain TeX, or learned how to work the TeX distribution to only install the stuff I needed. But ultimately it was just easier to get going with groff.

You can hack it with the \m[<color>] escape in groff:

         \m[blue]int\m[] x

Of course, you would use some kind of pre-processor to make this less of a PITA, but it's not inconceivable.