Legend of the Red Dragon (LoRD), Solar Realms Elite and Barren Realms Elite, and Tradewars were the best.
When I want to learn a new programming language, I always try to recreate Tradewars in it as a language. I know Tradewars like the back of my hand, so it allows me to focus on the nuances of the language while I build it. Such a fun project. The only thing I never quite figured out were the economics mechanics (it technically works, but it's a bit more predictable than TW2002 has in practice) and the Big Bang algorithm (I came up with my own, it's fine, but it doesn't have quite the same feel to it).
So much so that for several years I used a QB program I'd written to convert emails into QWK so I could use OLX to interact with emails. I'd reply using it and then convert my replies to plain text so I could send it off.
BlueWave had that annoying "Ride the BlueWave!" default tagline, though. It might have been the progenitor of the plague of "Sent from my Blackberry/iphone" spamminess a few decades later...
Becoming a point (or even a private node) was the more hardcore option - running a mailer and tosser to exchange bundles of mail with your upstream node using protocols like WaZoo and the gloriously-named YooHoo/2U2.
* https://en.everybodywiki.com/Blue_Wave_(mail_reader)
As well as the QWK and SOUP file formats (the latter when I started on Usenet as well):
* https://en.wikipedia.org/wiki/QWK_(file_format)
* https://web.archive.org/web/20080509070947/http://combee.tec...
And Tradewars 2002 'door game':
* https://en.wikipedia.org/wiki/Trade_Wars
* https://breakintochat.com/wiki/TradeWars_2002
* https://breakintochat.com/wiki/BBS_door_game
* https://en.wikipedia.org/wiki/Door_(bulletin_board_system)