Postal

Look past the highly effective marketing as the game the political class and talking heads on TV would be sure to be appalled by, and the eye-rollingly grim insane narration (the element later installments would drop to lean further into "wackiness"; the marching band was memorable absurdity, at least)... and what you've got is a somewhat clunky and highly repetitive arena shooter. Updates to the controls in later versions make the whole thing breeze by more easily, but it still is what it is.