Sharlto Copley apparently described this as the most challenging of his acting career, and I’m honestly not surprised at this, since Jimmy has so many different personalities in this.
Overall, I do love this movie. It rolls along with tight, fast pacing. Plenty of stunts and parkour and yeah, I could totally play this game even though I tend to prefer sandbox more than linear.
It is not for the fainthearted. Some brave soul has counted all 211 deaths and noted it as trivia on IMDB.
10 different stuntmen and cameramen played Henry. This is how they did it and I strongly encourage you to go at least skim this article at fxguide. It is pretty unique and I do have a very fond spot for this movie.