Like every other game ever written in history.
Not true but if it were it still wouldn't matter as the vast majority of games are 32-bit and use less than 1GB of RAM, let alone 4GB+
Contradicting yourself. There were a few games that pushed the limits of the PC and it took two more generations of processors and graphics cards to catch up. ID Software were good at that with Doom and Quake for example. Doom 3 will happily use 4gb and more if you have it, so too does Eve Online, try them on a 16Gb Ram system. Most games only used 1Gb because that's all Windows left free for it to use if you only had 4gb Ram. Thorw 16 on it and you'll get around 7Gb free. If you don't believe me, use a third party RAM checker, don't believe what the M$ one says, it lies.
Most of the limitations were Ram related, Windoze always has had the knack of using more memory than it really needs.
Way back in the days of the 486 we tried Windows 3.11 with different configurations of Ram. 1Mb (it wasn't gigabytes back then remember), and upwards to 8mb.
1Mb - Windows ran with a small amount of swap file usage. Left 300K for user.
2Mb - Windows ran with practically no swap file usage. Left just over 512K for user.
4Mb - Windows loaded unnecessary DLL's into Ram (contrary to how they were SUPPOSED to work), no Swap file use but around 1Mb for user.
8Mb - Yet more DLLs loaded no swap file use but only around 2mb for user.
So it seems the more RAM you throw at Windoze, the more it grabs for itself for unnecessary use. If it could run in 2Mb with limited swap file use and still leave 0.5mb for the users programs, why did it suddenly need 6Mb to run when you put 8mb RAM on it? Later versions of Windows, 95, 98, ME and right up to present day versions are no different, the more memory you throw at it, the more it grabs for itself.
To get the absolute best out of games, we really need a very basic OS that doesn't try to emulate an AI, wash the dishes and do the laundry and the shopping and nag you about answering your emails, sing, dance and ring bells, using significant resources to do so, while you're trying to play a game. GemOS was ideal, it was a GUI that did nothing more than Operate the System, it ran from a single floppy disk and was basically nothing but a hardware driver interface with a GUI front end. I believe it was the basis for the very successful MacOS, it was also used on the Atari ST. A sig line that I used to use was a dig at Microsoft:
"An OS is something that Operates the System, not a complete package of every piece of software ever written."