There are still a bunch of old MUDs (which are like multi-player text adventures) online.[1] A good list of the top 10 or 20 MUDs can be found here: [2], and a much bigger list can be found here: [3]

[1] - https://tmcchat.discoursehosting.net/t/old-muds-still-open/5...

[2] - http://www.mudconnect.com/#top10

[3] - http://www.mudconnect.com/cgi-bin/search.cgi?mode=tmc_biglis...