Now the online mode:
One thing first: The online mode is the firecracker! It's fun, because there is no longer AI, soldiers are controlled by other people from around the world. In the beginning a little difficult, but practice makes perfect :-).
And for the rest: The description says it all ;-). Only the minimum requirements of Electronic Arts are again completely failed. At 500 MHz probably nothing would work, 128 MB of RAM is not enough even for long. But a reasonably current PC is sufficient nowadays but slack off.
In summary: The offline mode is to settle more later but you should play online because the offline mode is boring.
The only prevention at the beginning: with the normal version does not klappts to play online. You need Battlefield 1942 patch to version 1.61, then you can play online. That should not be a problem for most but hopefully.
Overall, the game for me is just awesome! I play it very often, because it's so makes a fun.