Hi Niclas.
Most interactive fiction games which are called interactive fiction don't tend to work like the choiceofgames titles.They work by you typing commands.
You walk around usually by typing and then do things like examine object, open box etc.
usually you play them by loading the file in an interpreter. For example if it is a zcode game and the game's file has a z5 or z8 extention you need something like winfrotz or filfre to play, if it is a glks file you need something like winglulks etc.
As to where to find games, going to places like the interactive fiction wiki help. The if archive is just a huge file reposatory, but there are plenty of places which provide better info. There used to be a great site called baff's guide to the interactive fiction archive which provided pages for all the games,s olutions, information on interpreters etc.
For where to start I would recommend Andrew plotkin's game dream hold which you can play with winfrotz or filfre (I even heard there is an Ios version), since that game both serves as an introduction to if generally unlike a lot of other introductions isn't super simplistic or boring to play, indeed it's a wonderfully surreal where you play a wizard with no memory wandering around his castle trying to find various objects to discover what happened to him and peace together his last spell.
I will confess that personally I got to a point where i found if games more trouble than they were worth, since for every good game I found, i found four or five others where I just got utterly stuck, usually because I was trying to do something simple like put cup on table and getting messages like "I don't know how to put" however admitedly I've not played if games for a considerable time and there might be a lot of newer things out now.
Hth.
Sorry I can't be a little more specific, as I said, I've not played standard if of that sort for a good while, hopefully someone else has more recent information.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)