Yeah, I know, but it's like 15 years old, there were less standards back then.
Some of the ideas in the mod are still really good to this day though (and it's still kinda fun).
Like, if you step on a large healthkit or ammobox while being almost topped off on health or ammo of that type, you won't pick up and waste the entire pickup, you'll just leave the open box and you can come back and grab the rest of it later, you'll even see how many cartridges remain in an open box of shotgun shells.
I think it's probably also the first time anyone made an actually fragmenting grenade for Doom, and it's really useful, those fragments really fuck up pretty much anyone or anything that gets caught nearby, ESPECIALLY in tight quarters, where the fragments just bounce about and 'rip' like crazy, if there's a cyberdemon in a tight space, and if you can pitch in a couple of grenades in there (and take cover), that shrapnel will just fuck him (on the flip side, cybies also have itchier trigger fingers and faster, more powerful rockets, so this is even more dangerous to do).
All monsters also hurt you more, specters are sped up, all bullets hurt more, I feel it makes for higher stakes, it's harder, but it's not like Hideous Destructor hard.
I also love the flares, they can keep a dark and dank area lit up so you can get a good look of what's going on, what to run from or take cover from, what to shoot first.