Half Life 2 came out a year before Resurrection of Evil, so it's safe to say it was a ripoff.
It wasn't, but hey, whatever.
Anyway, I hope Doom 4 has more... idk, variation than Doom 3. I absolutely loved playing through Doom 3 the first time. Second time through however was just dull. The game relies a lot on surprises and cheap tricks, and even if it doesn't actually do them very well at all, it just worked on me. But second time through when you know what's coming up, it's not scary anymore and therefore isn't fun. I think the biggest issues with the game were enemies that were more like circus clowns than scary (
upside down faces with legs, and a goddamn slow as hell rocket launcher skeleton, I mean I know you want the enemies from the original back but this is
ridiculous) and also that most of them were no threat at all. The only enemies you were actually afraid of were the zombie soldiers, because they did almost unavoidable damage with their miniguns and tentacle arms.