Those looking for a heightened sense of challenge from BioShock Infinite will want to give the game's 1999 Mode a look. Although most players will gain access to this difficulty option by clearing the game normally, it can also be unlocked from the main menu through the following button inputs: Up, Up, Down, Down, Left, Right, Left, Right, (Cancel), (Confirm).
Irrational Games' design director Bill Gardner describes 1999 Mode as being "about approaching decisions with more caution. You have to choose which fights you can take on, along with which tools to specialize in, while committing to a long-term strategy."
I figure a fair amount of you who would want to dive right into the mode have started playing Infinite already, but if you haven't made it too far in yet, this is something to consider. Or maybe, like me, you have not yet cracked into your copy. Let's openly weep together.