All the Deus Ex games go for ridiculously cheap and are such a great fun-per-dollar ratio IMHO.
Yes, even Invisible War, if one embraces its weird consoley quirks. XD (bias: I enjoyed it on my OG Xbox back in the day. Universal ammo is so stupid though.)
Still gotta play Mankind Divided. I hope they finish the series one day. They absolutely nailed it with the iconic aesthetic, and Adam Jensen is just so freaking cool. :)