Looking good so far.
I like the theme.
main troubles include a little to loose lines, to much black and grey (to little colors - now disclaimer, Im no biggie on color either...) . But as itīs on its early stages, I guess those problems will settle.
Especially guns and hands are hard to depict with soft lines - I get the impression U added extra black computorlines over youre original pencils? Thats often completly unnecesary as things will settly by themselves (well, almost..." when more colours come on.
Even the grey concrete should have some stuff like brown waterpipes, redrusty iron, sunglare, redish sand and so on.
I see forward to update
. . . F I G H T - T H E - B O R E D O M . . .