I downloaded and tried Anarchy Online.
Anarchy Online is a Sci Fi MMO dating from 1991. It famously had one of the worst launches in MMO history although that is rather ancient history now. It used to be a subscription game and is now free-to-play. A quick glance at the microtransaction list suggests this is very much a game you enjoy extensively without paying unlike some F2P games which really require you to pay to get much fun out of them.
Anarchy Online has a very interesting backstory of a dystopian future. It has a wonderfully original and imaginative range of character classes based mainly on nanotech.
It didn't quite download right for me. I discovered afterwards that this is almost certainly because I was alt tabbed during the install. If you decide to try it install it when you have something to do that doesn't need the PC.
I could still have a look at it despite the download glitches (which messed up the display of chat).
It looks very dated indeed. It looks less up-to-date even than older games like Starcraft. I found the graphics very off-putting. I'm sure that would become less of an issue if you stuck with it for a few weeks but it's a high initial barrier.
The UI is very different from most other games. It's not a bad UI, it just clearly demands a lot of work to learn it. Another high initial barrier.
In the end after a brief look and inflicting some random violence on the local wildlife I decided not to re-download it. I do think it is one of the better free to play options if you are willing to learn the UI and adjust to the graphics.