If you own any of the Metro games
Play them on Hardcore and/or Realism/Ranger mode.
You die incredibly easy, but so do the enemies. Metro 2033 and friends adjust difficulty by scaling health and ammo drops around, but do not change fire rates or reload speed. This is what makes hordes so much harder, because it takes half a magazine to kill anything on normal difficulty, but only 2-3 shots on hardcore or realism.
Another bonus? It makes the knife actually viable. I've stepped in and melee'd a SUBSTANTIAL number of monsters to death, and gone through entire wildlife sections using almost nothing but. Knife fighting mutant horrors takes a little practice, but it feels good man, so good.
In a Metro related matter, other than grenade launchers and a few other things like magazines (most guns in the Metro use standard mags, so it's easier to just say "it takes these types" rather than listing stuff for every single gun.