"it is a good day to die" is the cheat code in WarCraft 2 that enables invincibility and makes all your units kill any enemy units in one hit.
"impulse 9" is the cheat code in the original Quake that gives you all the guns with full ammo and all keys.
If they don't bundle the micro-expansions for the retail market, I feel kind of bad for people who can't or won't buy things through Impulse.