Mr.Do! Is quite fun.

H.E.R.O. can become quite fun if you don’t mind initially learning its tricks through trial and error (the harder path is always the correct one). It can get pretty flow-state when you get a handle on it.

The early Space Quest from Sierra games are still quite fun if you don’t mind using a text parser. As is Quest for Glory.

Finally, a Mind Forever Voyaging by Infocom still holds up supremely well if you don’t mind pure text adventures. The short story included in the manual alone is worth the read.