I recently played through every Deus Ex game on linux, first 2 are oibviously low end, and maybe Human Revolution , it came out in 2011. the original and Human revolution are pretty good if you like rpgs, Invisible war the second game is alright but pretty light on some elements that make those two great, cause it was made i think with thje original xbox in mind instead of pc.
Depends, i dont think theres any missions where not using stealth fails the mission. You usually get a choice, but not using stealth can have story consequences in some cases, theres nothing really that makes it feel like it super matters cause the endings you get i believe end up being the same regardless ( all ill say to avoid spoilers) , but not using stealth can have consequences in your interactions with story characters, and the other interactions not related to the main story.
However you are free to blast your way through enemies if you so desire, as i recall. It does however make things more difficult in a few missions.