'DOOM 4' eventually became just DOOM at some point during its development, as legendary dev id Software rebooted the series back in 2016, dropping any sort of subtitle. The game essentially reinvented the franchise after DOOM 3, but at one stage, the title was much, much closer to the 'survival horror' style of the previous series entry.
As seen in a new leaked concept trailer, DOOM 2016 was once planned as a more direct sequel to DOOM 3 - even baring the number four in its title. It was also much darker in tone compared to what we eventually got. Here, take a look (headphone users beware, it's pretty loud):
This clip was first spotted on an id Software developer's Artstation page, although the original has now been removed. Of course, the internet sees what the internet sees, and now this relic of DOOM development is archived for all to see!
This is a very interesting look back at what became a pivotal development period for id Software. In the end, we absolutely loved how 'DOOM 4' turned out — and it's sequel DOOM Eternal for that matter — but still, things could have been very different it seems.
Id Software is now under Xbox ownership via Bethesda, which makes us even more intrigued by what's next for the longtime DOOM developer. Hopefully we see something from them soon enough!