Nothing like going Rambo through the Strogg Palace and deciding to blaze through it on Hard difficulty, and willingly going in and destroying all their ranks (I think on Hard there's a total of 300 mostly elites (different color than the garden variety Strogg, so I assume they were faster/stronger. Certainly took more hits than usual) during the final cluster of levels) and then Makron himself without using any powerups (Shield belt (had like 7 of them, sparing them unless a battle called for it; *cough*almost never*cough*), Quad Damage, Silencer, etc., had them all), and making the final battle a fair one-on-one Terran weapons (First 5 weapons) vs. Strogg weapons (Last 5 Weapons)) duel (again, no powerups used here); actually, make that for pretty much the entire game, I went through as a No Carry-on Powerups play (except Adrenaline life refills (just like Doom berserk packs; instant use on pickup). I wasn't aware the shield belt would be that useful to the point I wouldn't need to heal nearly as much as I had to and also doubling my armor rating while at it. I'm more badass than I thought. Especially when plowing through the front door of the palace, when I was up against 4 elite commanders, a few jetpacks, and a platoon of grunts (a total of maybe 25 dudes of varied ranks all at once at the front door, evading and shooting while completely surrounded and overwhelmed. Ate all the med packs at the opening doorway to heal up afterwards (knocked down to 25> health and almost no armor), but damn, was that fun.), and I shotgunned through the ranks like they were nothing. Cherry-tapping some of the ranks with the starter pistol was also pretty amusing; but handy as well, though. That sucker may be weak as hell, but it's really damn accurate at a distance, and probably the most useful weapon I used throughout the final raid; especially when out of view or range of certain Strogg.
Quake II
Hard Mode, No Use of Carry-on Powerups (by choice; part challenge, part overly-conservative playing (an old, and not-too-good habit of mine when playing))
I replayed the level with multiplayer settings as more of a level-select mode to relive it; also justifying the 'Give All' command (gives everything), since I was already like that when I initially raided it, and re-lived the experience how it was meant to be played (with powerups, this time, where appropriate). I liked my no-powerups run better. That was hardcore fun.
Funny how I can justify cheating post-beating the game (although beating the game itself is enough justification, on it's own, for me) by using the cheats to replicate my old setup if I lost a save (even on Hard, I was completely loaded by endgame + bandolier and backpack (1.5x-2x ammo capacity).