BatMUD is a text-based medieval fantasy massively multiplayer online game with an extremely rich set of features - constantly in development since 1990. It's a role-playing game produced by Antti A. Luostarinen and published by Balanced Alternative Techniques ry in 2019.
The system requirements are light; almost any new computers will work for playing BatMUD.
The RAM requirement of 4gb is easily covered.
The game requires almost no hard drive space.